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Banerjee S, Ghoshal S, Stevens JR, McCommis KS, Gao S, Castro-Sepulveda M, Mizgier ML, Girardet C, Kumar KG, Galgani JE, Niehoff ML, Farr SA, Zhang J, Butler AA. Hepatocyte expression of the micropeptide adropin regulates the liver fasting response and is enhanced by caloric restriction. J Biol Chem 2020; 295:13753-13768. [PMID: 32727846 DOI: 10.1074/jbc.ra120.014381] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 07/22/2020] [Indexed: 12/16/2022] Open
Abstract
The micropeptide adropin encoded by the clock-controlled energy homeostasis-associated gene is implicated in the regulation of glucose metabolism. However, its links to rhythms of nutrient intake, energy balance, and metabolic control remain poorly defined. Using surveys of Gene Expression Omnibus data sets, we confirm that fasting suppresses liver adropin expression in lean C57BL/6J (B6) mice. However, circadian rhythm data are inconsistent. In lean mice, caloric restriction (CR) induces bouts of compulsive binge feeding separated by prolonged fasting intervals, increasing NAD-dependent deacetylase sirtuin-1 signaling important for glucose and lipid metabolism regulation. CR up-regulates adropin expression and induces rhythms correlating with cellular stress-response pathways. Furthermore, adropin expression correlates positively with phosphoenolpyruvate carboxokinase-1 (Pck1) expression, suggesting a link with gluconeogenesis. Our previous data suggest that adropin suppresses gluconeogenesis in hepatocytes. Liver-specific adropin knockout (LAdrKO) mice exhibit increased glucose excursions following pyruvate injections, indicating increased gluconeogenesis. Gluconeogenesis is also increased in primary cultured hepatocytes derived from LAdrKO mice. Analysis of circulating insulin levels and liver expression of fasting-responsive cAMP-dependent protein kinase A (PKA) signaling pathways also suggests enhanced responses in LAdrKO mice during a glucagon tolerance test (250 µg/kg intraperitoneally). Fasting-associated changes in PKA signaling are attenuated in transgenic mice constitutively expressing adropin and in fasting mice treated acutely with adropin peptide. In summary, hepatic adropin expression is regulated by nutrient- and clock-dependent extrahepatic signals. CR induces pronounced postprandial peaks in hepatic adropin expression. Rhythms of hepatic adropin expression appear to link energy balance and cellular stress to the intracellular signal transduction pathways that drive the liver fasting response.
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Affiliation(s)
- Subhashis Banerjee
- Department of Pharmacology and Physiology, Saint Louis University School of Medicine, St. Louis, Missouri, USA
| | - Sarbani Ghoshal
- Department of Pharmacology and Physiology, Saint Louis University School of Medicine, St. Louis, Missouri, USA
| | - Joseph R Stevens
- Department of Pharmacology and Physiology, Saint Louis University School of Medicine, St. Louis, Missouri, USA
| | - Kyle S McCommis
- Edward A. Doisy Department of Biochemistry and Molecular Biology, Saint Louis University School of Medicine, St. Louis, Missouri, USA; Center for Cardiovascular Research, Saint Louis University School of Medicine, St. Louis, Missouri, USA; Saint Louis University Liver Center, Saint Louis University School of Medicine, St. Louis, Missouri USA
| | - Su Gao
- Department of Metabolism and Aging, Scripps Research Institute, Jupiter, Florida, USA
| | - Mauricio Castro-Sepulveda
- Laboratorio de Ciencias del Ejercicio. Facultad de Medicina, Universidad Finis Terrae, Santiago, Chile
| | - Maria L Mizgier
- Departamento de Ciencias de la SaludCarrera de Nutrición y Dietética and Departamento de Nutrición, Diabetes y Metabolismo, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Clemence Girardet
- Department of Pharmacology and Physiology, Saint Louis University School of Medicine, St. Louis, Missouri, USA
| | - K Ganesh Kumar
- Department of Metabolism and Aging, Scripps Research Institute, Jupiter, Florida, USA
| | - Jose E Galgani
- Departamento de Ciencias de la SaludCarrera de Nutrición y Dietética and Departamento de Nutrición, Diabetes y Metabolismo, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Michael L Niehoff
- Henry and Amelia Nasrallah Center for Neuroscience, Saint Louis University School of Medicine, St. Louis, Missouri, USA; Division of Geriatric Medicine, Saint Louis University School of Medicine, St. Louis, Saint Louis University School of Medicine; Research Service, John Cochran Division, Saint Louis Veterans Affairs Medical Center, Missouri, USA
| | - Susan A Farr
- Henry and Amelia Nasrallah Center for Neuroscience, Saint Louis University School of Medicine, St. Louis, Missouri, USA; Division of Geriatric Medicine, Saint Louis University School of Medicine, St. Louis, Saint Louis University School of Medicine; Research Service, John Cochran Division, Saint Louis Veterans Affairs Medical Center, Missouri, USA
| | - Jinsong Zhang
- Department of Pharmacology and Physiology, Saint Louis University School of Medicine, St. Louis, Missouri, USA
| | - Andrew A Butler
- Department of Pharmacology and Physiology, Saint Louis University School of Medicine, St. Louis, Missouri, USA; Department of Metabolism and Aging, Scripps Research Institute, Jupiter, Florida, USA; Henry and Amelia Nasrallah Center for Neuroscience, Saint Louis University School of Medicine, St. Louis, Missouri, USA.
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2
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Oncogenic lncRNA downregulates cancer cell antigen presentation and intrinsic tumor suppression. Nat Immunol 2019; 20:835-851. [PMID: 31160797 PMCID: PMC6619502 DOI: 10.1038/s41590-019-0400-7] [Citation(s) in RCA: 234] [Impact Index Per Article: 46.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Accepted: 04/12/2019] [Indexed: 12/12/2022]
Abstract
The mechanisms through which tumor cells genetically lose antigenicity and evade immune checkpoints remain largely elusive. Here, we report that tissue-specific expression of the human long-noncoding RNA LINK-A in mouse mammary glands initiated metastatic mammary gland tumors, which phenotypically resembled human triple-negative breast cancer (TNBC). LINK-A expression facilitated crosstalk between phosphatidylinositol-(3,4,5)-trisphosphate and inhibitory G-protein–coupled receptor (GPCR) pathways, attenuating protein kinase A (PKA)-mediated phosphorylation of the E3 ubiquitin ligase TRIM71. Consequently, LINK-A expression enhanced K48–polyubiquitination-mediated degradation of the antigen peptide-loading complex (PLC) and intrinsic tumor suppressors Rb and p53. Treatment with LINK-A-locked nucleic acids or GPCR antagonists stabilized the PLC components, Rb, and p53, and sensitized mammary gland tumors to immune checkpoint blockers (ICBs). Importantly, PD-1 blockade-resistant TNBC patients exhibited elevated LINK-A levels and downregulated PLC components. Hence, we demonstrated lncRNA-dependent downregulation of antigenicity and intrinsic tumor suppression, which may provide the basis for developing a therapeutic regimen of combinational immunotherapy and effective early prevention for TNBCs.
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Vishwanath S, de Brevern AG, Srinivasan N. Same but not alike: Structure, flexibility and energetics of domains in multi-domain proteins are influenced by the presence of other domains. PLoS Comput Biol 2018; 14:e1006008. [PMID: 29432415 PMCID: PMC5825166 DOI: 10.1371/journal.pcbi.1006008] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Revised: 02/23/2018] [Accepted: 01/29/2018] [Indexed: 02/01/2023] Open
Abstract
The majority of the proteins encoded in the genomes of eukaryotes contain more than one domain. Reasons for high prevalence of multi-domain proteins in various organisms have been attributed to higher stability and functional and folding advantages over single-domain proteins. Despite these advantages, many proteins are composed of only one domain while their homologous domains are part of multi-domain proteins. In the study presented here, differences in the properties of protein domains in single-domain and multi-domain systems and their influence on functions are discussed. We studied 20 pairs of identical protein domains, which were crystallized in two forms (a) tethered to other proteins domains and (b) tethered to fewer protein domains than (a) or not tethered to any protein domain. Results suggest that tethering of domains in multi-domain proteins influences the structural, dynamic and energetic properties of the constituent protein domains. 50% of the protein domain pairs show significant structural deviations while 90% of the protein domain pairs show differences in dynamics and 12% of the residues show differences in the energetics. To gain further insights on the influence of tethering on the function of the domains, 4 pairs of homologous protein domains, where one of them is a full-length single-domain protein and the other protein domain is a part of a multi-domain protein, were studied. Analyses showed that identical and structurally equivalent functional residues show differential dynamics in homologous protein domains; though comparable dynamics between in-silico generated chimera protein and multi-domain proteins were observed. From these observations, the differences observed in the functions of homologous proteins could be attributed to the presence of tethered domain. Overall, we conclude that tethered domains in multi-domain proteins not only provide stability or folding advantages but also influence pathways resulting in differences in function or regulatory properties. High prevalence of multi-domain proteins in proteomes has been attributed to higher stability and functional and folding advantages of the multi-domain proteins. Influence of tethering of domains on the overall properties of proteins has been well studied but its influence on the properties of the constituent domains is largely unaddressed. Here, we investigate the influence of tethering of domains in multi-domain proteins on the structural, dynamics and energetics properties of the constituent domains and its implications on the functions of proteins. To this end, comparative analyses were carried out for identical protein domains crystallized in tethered and untethered forms. Also, comparative analyses of single-domain proteins and their homologous multi-domain proteins were performed. The analyses suggest that tethering influences the structural, dynamic and energetic properties of constituent protein domains. Our observations hint at regulation of protein domains by tethered domains in multi-domain systems, which may manifest at the differential function observed between single-domain and homologous multi-domain proteins.
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Grants
- IISc-DBT partnership programme
- DST, India (Mathematical Biology Initiative & J.C. Bose National Fellowship, FIST program)
- UGC, India – Centre for Advanced Studies
- Ministry of Human Resource Development
- Ministry of Research (France), University of Paris Diderot, Sorbonne Paris Cité
- National Institute for Blood Transfusion (INTS, France), Institute for Health and Medical Research (INSERM, France), Laboratory of Excellence GR-Ex
- The labex GR-Ex is funded by the program Investissements d’avenir of the French National Research Agency,
- Indo-French Centre for the Promotion of Advanced Research/CEFIPRA for a collaborative grant
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Affiliation(s)
- Sneha Vishwanath
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore, India
| | - Alexandre G. de Brevern
- INSERM, U 1134, DSIMB, Paris, France
- Univ. Paris Diderot, Sorbonne Paris Cité, Univ de la Réunion, Univ des Antilles, UMR_S 1134, Paris, France
- Institut National de la Transfusion Sanguine (INTS), Paris, France
- Laboratoire d' Excellence GR-Ex, Paris, France
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Tsuda T, Takefuji M, Wettschureck N, Kotani K, Morimoto R, Okumura T, Kaur H, Eguchi S, Sakaguchi T, Ishihama S, Kikuchi R, Unno K, Matsushita K, Ishikawa S, Offermanns S, Murohara T. Corticotropin releasing hormone receptor 2 exacerbates chronic cardiac dysfunction. J Exp Med 2017; 214:1877-1888. [PMID: 28550160 PMCID: PMC5502432 DOI: 10.1084/jem.20161924] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Revised: 03/09/2017] [Accepted: 04/12/2017] [Indexed: 12/20/2022] Open
Abstract
Prognosis of patients with chronic heart failure remains poor, emphasizing the need to identify additional pathophysiological factors. Tsuda et al. show that Crhr2 activation causes cardiac dysfunction and suggest Crhr2 blockade is a promising therapeutic strategy for chronic heart failure. Heart failure occurs when the heart is unable to effectively pump blood and maintain tissue perfusion. Despite numerous therapeutic advancements over previous decades, the prognosis of patients with chronic heart failure remains poor, emphasizing the need to identify additional pathophysiological factors. Here, we show that corticotropin releasing hormone receptor 2 (Crhr2) is a G protein–coupled receptor highly expressed in cardiomyocytes and continuous infusion of the Crhr2 agonist, urocortin 2 (Ucn2), reduced left ventricular ejection fraction in mice. Moreover, plasma Ucn2 levels were 7.5-fold higher in patients with heart failure compared to those in healthy controls. Additionally, cardiomyocyte-specific deletion of Crhr2 protected mice from pressure overload-induced cardiac dysfunction. Mice treated with a Crhr2 antagonist lost maladaptive 3′-5′-cyclic adenosine monophosphate (cAMP)–dependent signaling and did not develop heart failure in response to overload. Collectively, our results indicate that constitutive Crhr2 activation causes cardiac dysfunction and suggests that Crhr2 blockade is a promising therapeutic strategy for patients with chronic heart failure.
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Affiliation(s)
- Takuma Tsuda
- Department of Cardiology, Nagoya University School of Medicine, Nagoya, Japan
| | - Mikito Takefuji
- Department of Cardiology, Nagoya University School of Medicine, Nagoya, Japan
| | - Nina Wettschureck
- Department of Pharmacology, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany
| | - Kazuhiko Kotani
- Center for Community Medicine, Jichi Medical University, Shimotsuke, Japan
| | - Ryota Morimoto
- Department of Cardiology, Nagoya University School of Medicine, Nagoya, Japan
| | - Takahiro Okumura
- Department of Cardiology, Nagoya University School of Medicine, Nagoya, Japan
| | - Harmandeep Kaur
- Department of Pharmacology, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany
| | - Shunsuke Eguchi
- Department of Cardiology, Nagoya University School of Medicine, Nagoya, Japan
| | - Teruhiro Sakaguchi
- Department of Cardiology, Nagoya University School of Medicine, Nagoya, Japan
| | - Sohta Ishihama
- Department of Cardiology, Nagoya University School of Medicine, Nagoya, Japan
| | - Ryosuke Kikuchi
- Department of Medical Technique, Nagoya University Hospital, Nagoya, Japan
| | - Kazumasa Unno
- Department of Cardiology, Nagoya University School of Medicine, Nagoya, Japan
| | - Kunihiro Matsushita
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD
| | - Shizukiyo Ishikawa
- Center for Community Medicine, Jichi Medical University, Shimotsuke, Japan
| | - Stefan Offermanns
- Department of Pharmacology, Max Planck Institute for Heart and Lung Research, Bad Nauheim, Germany
| | - Toyoaki Murohara
- Department of Cardiology, Nagoya University School of Medicine, Nagoya, Japan
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5
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A Novel Phosphoregulatory Switch Controls the Activity and Function of the Major Catalytic Subunit of Protein Kinase A in Aspergillus fumigatus. mBio 2017; 8:mBio.02319-16. [PMID: 28174315 PMCID: PMC5296607 DOI: 10.1128/mbio.02319-16] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Invasive aspergillosis (IA), caused by the filamentous fungal pathogen Aspergillus fumigatus, is a major cause of death among immunocompromised patients. The cyclic AMP/protein kinase A (PKA) signaling pathway is essential for hyphal growth and virulence of A. fumigatus, but the mechanism of regulation of PKA remains largely unknown. Here, we discovered a novel mechanism for the regulation of PKA activity in A. fumigatus via phosphorylation of key residues within the major catalytic subunit, PkaC1. Phosphopeptide enrichment and tandem mass spectrometry revealed the phosphorylation of PkaC1 at four sites (S175, T331, T333, and T337) with implications for important and diverse roles in the regulation of A. fumigatus PKA. While the phosphorylation at one of the residues (T333) is conserved in other species, the identification of three other residues represents previously unknown PKA phosphoregulation in A. fumigatus Site-directed mutagenesis of the phosphorylated residues to mimic or prevent phosphorylation revealed dramatic effects on kinase activity, growth, conidiation, cell wall stress response, and virulence in both invertebrate and murine infection models. Three-dimensional structural modeling of A. fumigatus PkaC1 substantiated the positive or negative regulatory roles for specific residues. Suppression of PKA activity also led to downregulation of PkaC1 protein levels in an apparent novel negative-feedback mechanism. Taken together, we propose a model in which PkaC1 phosphorylation both positively and negatively modulates its activity. These findings pave the way for future discovery of fungus-specific aspects of this key signaling network. IMPORTANCE Our understanding of signal transduction networks in pathogenic fungi is limited, despite the increase in invasive fungal infections and rising mortality rates in the immunosuppressed patient population. Because PKA is known to be essential for hyphal growth and virulence of A. fumigatus, we sought to identify fungus-specific regulatory mechanisms governing PKA activity. In this study, we identify, for the first time, a novel mechanism for the regulation of PKA signaling in which differential phosphorylation of the PkaC1 catalytic subunit can lead to either positive or negative regulation of activity. Furthermore, we show that inactivation of PKA signaling leads to downregulation of catalytic subunit protein levels in a negative-feedback mechanism distinct from expression patterns previously reported in the yeasts. Our findings represent a divergence in the regulation of PKA signaling in A. fumigatus, which could potentially be exploited as a target and also open the avenue for discovery of fungus-specific downstream effectors of PKA.
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6
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Jing YP, Wang D, Han XL, Dong DJ, Wang JX, Zhao XF. The Steroid Hormone 20-Hydroxyecdysone Enhances Gene Transcription through the cAMP Response Element-binding Protein (CREB) Signaling Pathway. J Biol Chem 2016; 291:12771-12785. [PMID: 27129227 DOI: 10.1074/jbc.m115.706028] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Indexed: 11/06/2022] Open
Abstract
Animal steroid hormones regulate gene transcription through genomic pathways by binding to nuclear receptors. These steroid hormones also rapidly increase intracellular calcium and cyclic adenosine monophosphate (cAMP) levels and activate the protein kinase C (PKC) and protein kinase A (PKA) nongenomic pathways. However, the function and mechanism of the nongenomic pathways of the steroid hormones are unclear, and the relationship between the PKC and PKA pathways is also unclear. We propose that the steroid hormone 20-hydroxyecdysone (20E) activates the PKA pathway to enhance 20E-induced gene transcription in the lepidopteran insect Helicoverpa armigera The expression of the catalytic subunit 1 of PKA (PKAC1) increased during metamorphosis, and PKAC1 knockdown blocked pupation and repressed 20E-responsive gene expression. 20E regulated PKAC1 phosphorylation at threonine 200 and nuclear translocation through an ecdysone-responsive G-protein-coupled receptor 2. PKAC1 induced cAMP response element-binding protein (CREB) phosphorylation at serine 143, which bound to the cAMP response element on DNA to enhance 20E-responsive gene transcription. Through ecdysone-responsive G-protein-coupled receptor 2, 20E increased cAMP levels, which induced CREB PKA phosphorylation and 20E-responsive gene expression. This study demonstrates that the PKA/CREB pathway tightly and critically regulates 20E-induced gene transcription as well as its relationship with the 20E-induced PKC pathway.
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Affiliation(s)
- Yu-Pu Jing
- From the Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Jinan 250100, China
| | - Di Wang
- From the Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Jinan 250100, China
| | - Xiao-Lin Han
- From the Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Jinan 250100, China
| | - Du-Juan Dong
- From the Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Jinan 250100, China
| | - Jin-Xing Wang
- From the Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Jinan 250100, China
| | - Xiao-Fan Zhao
- From the Shandong Provincial Key Laboratory of Animal Cells and Developmental Biology, School of Life Sciences, Shandong University, Jinan 250100, China.
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An BC, Sakai T, Komaba S, Kishi H, Kobayashi S, Kim JY, Ikebe R, Ikebe M. Phosphorylation of the kinase domain regulates autophosphorylation of myosin IIIA and its translocation in microvilli. Biochemistry 2014; 53:7835-45. [PMID: 25402663 PMCID: PMC4270376 DOI: 10.1021/bi501247z] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
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Motor activity of myosin III is regulated
by autophosphorylation.
To investigate the role of the kinase activity on the transporter
function of myosin IIIA (Myo3A), we identified the phosphorylation
sites of kinase domain (KD), which is responsible for the regulation
of kinase activity and thus motor function. Using mass spectrometry,
we identified six phosphorylation sites in the KD, which are highly
conserved among class III myosins and Ste20-related misshapen (Msn)
kinases. Two predominant sites, Thr184 and Thr188, in KD are important for phosphorylation of the KD as well as the
motor domain, which regulates the affinity for actin. In the Caco2
cells, the full-length human Myo3A (hMyo3AFull) markedly enlarged
the microvilli, although it did not show discrete localization within
the microvilli. On the other hand, hMyo3AFull(T184A) and hMyo3AFull(T188A)
both showed clear localization at the microvilli tips. Our results
suggest that Myo3A induces large actin bundle formation to form microvilli,
and phosphorylation of KD at Thr184 and Thr188 is critical for the kinase activity of Myo3A, and regulation of
Myo3A translocation to the tip of microvilli. Retinal extracts potently
dephosphorylate both KD and motor domain without IQ motifs (MDIQo),
which was inhibited by okadaic acid (OA) with nanomolar range and
by tautomycetin (TMC) with micromolar range. The results suggest that
Myo3A phosphatase is protein phosphatase type 2A (PP2A). Supporting
this result, recombinant PP2Ac potently dephosphorylates both KD and
MDIQo. We propose that the phosphorylation–dephosphorylation
mechanism plays an essential role in mediating the transport and actin
bundle formation and stability functions of hMyo3A.
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Affiliation(s)
- Byung Chull An
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School , Worcester, Massachusetts 01605, United States
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Cushing L, Stochaj W, Siegel M, Czerwinski R, Dower K, Wright Q, Hirschfield M, Casanova JL, Picard C, Puel A, Lin LL, Rao VR. Interleukin 1/Toll-like receptor-induced autophosphorylation activates interleukin 1 receptor-associated kinase 4 and controls cytokine induction in a cell type-specific manner. J Biol Chem 2014; 289:10865-10875. [PMID: 24567333 DOI: 10.1074/jbc.m113.544809] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
IRAK4 is a central kinase in innate immunity, but the role of its kinase activity is controversial. The mechanism of activation for IRAK4 is currently unknown, and little is known about the role of IRAK4 kinase in cytokine production, particularly in different human cell types. We show IRAK4 autophosphorylation occurs by an intermolecular reaction and that autophosphorylation is required for full catalytic activity of the kinase. Phosphorylation of any two of the residues Thr-342, Thr-345, and Ser-346 is required for full activity, and the death domain regulates the activation of IRAK4. Using antibodies against activated IRAK4, we demonstrate that IRAK4 becomes phosphorylated in human cells following stimulation by IL-1R and Toll-like receptor agonists, which can be blocked pharmacologically by a dual inhibitor of IRAK4 and IRAK1. Interestingly, in dermal fibroblasts, although complete inhibition of IRAK4 kinase activity does not inhibit IL-1-induced IL-6 production, NF-κB, or MAPK activation, there is complete ablation of these processes in IRAK4-deficient cells. In contrast, the inhibition of IRAK kinase activity in primary human monocytes reduces R848-induced IL-6 production with minimal effect on NF-κB or MAPK activation. Taken together, these studies define the mechanism of IRAK4 activation and highlight the differential role of IRAK4 kinase activity in different human cell types as well as the distinct roles IRAK4 scaffolding and kinase functions play.
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Affiliation(s)
- Leah Cushing
- Inflammation and Remodeling Research Unit, Pfizer Research, Cambridge, Massachusetts 02140
| | - Wayne Stochaj
- Global Biological Technology, Pfizer Research, Cambridge, Massachusetts 02140
| | - Marshall Siegel
- Pfizer Chemical Technologies Section, Pearl River, New York 10965
| | - Robert Czerwinski
- Inflammation and Remodeling Research Unit, Pfizer Research, Cambridge, Massachusetts 02140
| | - Ken Dower
- Inflammation and Remodeling Research Unit, Pfizer Research, Cambridge, Massachusetts 02140
| | - Quentin Wright
- Inflammation and Remodeling Research Unit, Pfizer Research, Cambridge, Massachusetts 02140
| | - Margaret Hirschfield
- Inflammation and Remodeling Research Unit, Pfizer Research, Cambridge, Massachusetts 02140
| | - Jean-Laurent Casanova
- St. Giles Laboratory of Human Genetics of Infectious Diseases Howard Hughes Medical Institute, Rockefeller University, New York, New York 10065; Howard Hughes Medical Institute, Rockefeller University, New York, New York 10065; Pediatric Hematology-Immunology Unit, Assistance Publique Hôpitaux de Paris, Necker Hospital, Paris 75015, France; Laboratory of Human Genetics of Infectious Diseases, Imagine Institute, Assistance Publique Hôpitaux de Paris, Necker Hospital, Paris 75015, France; University of Paris at Descartes, Paris 75006, France
| | - Capucine Picard
- Laboratory of Human Genetics of Infectious Diseases, Imagine Institute, Assistance Publique Hôpitaux de Paris, Necker Hospital, Paris 75015, France; Study Center for Primary Immunodeficiencies, Assistance Publique Hôpitaux de Paris, Necker Hospital, Paris 75015, France; University of Paris at Descartes, Paris 75006, France
| | - Anne Puel
- St. Giles Laboratory of Human Genetics of Infectious Diseases Howard Hughes Medical Institute, Rockefeller University, New York, New York 10065; Laboratory of Human Genetics of Infectious Diseases, Imagine Institute, Assistance Publique Hôpitaux de Paris, Necker Hospital, Paris 75015, France; University of Paris at Descartes, Paris 75006, France
| | - Lih-Ling Lin
- Inflammation and Remodeling Research Unit, Pfizer Research, Cambridge, Massachusetts 02140.
| | - Vikram R Rao
- Inflammation and Remodeling Research Unit, Pfizer Research, Cambridge, Massachusetts 02140.
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9
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Meharena HS, Chang P, Keshwani MM, Oruganty K, Nene AK, Kannan N, Taylor SS, Kornev AP. Deciphering the structural basis of eukaryotic protein kinase regulation. PLoS Biol 2013; 11:e1001680. [PMID: 24143133 PMCID: PMC3797032 DOI: 10.1371/journal.pbio.1001680] [Citation(s) in RCA: 161] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Accepted: 08/29/2013] [Indexed: 02/07/2023] Open
Abstract
Biochemical and structural analysis of two features of kinase structure, the “R-spine” and “Shell,” afford a detailed insight into the regulation of eukaryotic protein kinases. Eukaryotic protein kinases (EPKs) regulate numerous signaling processes by phosphorylating targeted substrates through the highly conserved catalytic domain. Our previous computational studies proposed a model stating that a properly assembled nonlinear motif termed the Regulatory (R) spine is essential for catalytic activity of EPKs. Here we define the required intramolecular interactions and biochemical properties of the R-spine and the newly identified “Shell” that surrounds the R-spine using site-directed mutagenesis and various in vitro phosphoryl transfer assays using cyclic AMP-dependent protein kinase as a representative of the entire kinome. Analysis of the 172 available Apo EPK structures in the protein data bank (PDB) revealed four unique structural conformations of the R-spine that correspond with catalytic inactivation of various EPKs. Elucidating the molecular entities required for the catalytic activation of EPKs and the identification of these inactive conformations opens new avenues for the design of efficient therapeutic EPK inhibitors. Eukaryotic protein kinases (EPKs) have a highly conserved enzymatic kinase core that is involved in the regulation of numerous cell signaling processes through the transfer of a phosphate group from adenosine triphosphate (ATP) to more than 30% of human proteins. EPKs have been implicated in numerous human diseases, including cancer, cardiovascular diseases, and diabetes, making them one of the most sought-after therapeutic drug targets. The lack of structural diversity of the active kinase core has created a bottle-neck for designing successful therapeutic inhibitors. Here we describe the intramolecular interactions required for differentiating between the active and inactive states of EPKs. Kinases contain a hydrophobic regulatory spine (“R-spine”) that is disassembled in inactive kinases, and here we define an additional hydrophobic “Shell” that surrounds one end of the R-spine. Biochemical analysis of the five nonconsecutive R-spine residues and three nonconsecutive Shell residues shows that proper assembly of the R-spine and Shell is essential for maintaining kinase activity. Structural analysis of the 172 known structures of EPKs without bound ligands led to the identification of four inactive conformations that correlate with the disassembly of the R-spine. Understanding the molecular elements involved in the regulation of kinase activity and the identification of these diverse groups of inactive conformations should aid the design of more specific therapeutic EPK inhibitors.
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Affiliation(s)
- Hiruy S Meharena
- Biomedical Sciences, University of California, San Diego, La Jolla, California, United States of America
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10
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Stone JD, Narine A, Tulis DA. Inhibition of vascular smooth muscle growth via signaling crosstalk between AMP-activated protein kinase and cAMP-dependent protein kinase. Front Physiol 2012; 3:409. [PMID: 23112775 PMCID: PMC3482697 DOI: 10.3389/fphys.2012.00409] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2012] [Accepted: 10/03/2012] [Indexed: 11/25/2022] Open
Abstract
Abnormal vascular smooth muscle (VSM) growth is central in the pathophysiology of vascular disease yet fully effective therapies to curb this growth are lacking. Recent findings from our lab and others support growth control of VSM by adenosine monophosphate (AMP)-based approaches including the metabolic sensor AMP-activated protein kinase (AMPK) and cAMP-dependent protein kinase (PKA). Molecular crosstalk between AMPK and PKA has been previously suggested, yet the extent to which this occurs and its biological significance in VSM remain unclear. Considering their common AMP backbone and similar signaling characteristics, we hypothesized that crosstalk exists between AMPK and PKA in the regulation of VSM growth. Using rat primary VSM cells (VSMC), the AMPK agonist AICAR increased AMPK activity and phosphorylation of the catalytic Thr172 site on AMPK. Interestingly, AICAR also phosphorylated a suspected PKA-inhibitory Ser485 site on AMPK, and these cumulative events were reversed by the PKA inhibitor PKI suggesting possible PKA-mediated regulation of AMPK. AICAR also increased PKA activity in a reversible fashion. The cAMP stimulator forskolin increased PKA activity and completely ameliorated Ser/Thr protein phosphatase-2C activity, suggesting a potential mechanism of AMPK modulation by PKA since inhibition of PKA by PKI reduced AMPK activity. Functionally, AMPK inhibited serum-stimulated cell cycle progression and cellular proliferation; however, PKA failed to do so. Moreover, AMPK and PKA reduced PDGF-β-stimulated VSMC migration. Collectively, these results show that AMPK is capable of reducing VSM growth in both anti-proliferative and anti-migratory fashion. Furthermore, these data suggest that AMPK may be modulated by PKA and that positive feedback may exist between these two systems. These findings reveal a discrete nexus between AMPK and PKA in VSM and provide basis for metabolically-directed targets in reducing pathologic VSM growth.
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Affiliation(s)
- Joshua D Stone
- Department of Physiology, Brody School of Medicine, East Carolina University Greenville, NC, USA
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11
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Ji R, Sanchez CM, Chou CL, Chen XB, Woodward DF, Regan JW. Prostanoid EP₁ receptors mediate up-regulation of the orphan nuclear receptor Nurr1 by cAMP-independent activation of protein kinase A, CREB and NF-κB. Br J Pharmacol 2012; 166:1033-46. [PMID: 22188298 DOI: 10.1111/j.1476-5381.2011.01817.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND AND PURPOSE Prostaglandin E(2) (PGE(2)) stimulation of the G protein-coupled prostanoid EP(1) receptor was found to up-regulate the expression of Nur-related factor 1 (Nurr1) (NR4A2), a transcription factor in the NR4A subfamily of nuclear receptors. The present studies characterize the molecular mechanism of this up-regulation. EXPERIMENTAL APPROACH The expression of Nurr1 was examined by immunoblot analysis, the polymerase chain reaction and reporter gene assays in human embryonic kidney (HEK) cells stably expressing the recombinant EP(1) receptor and in SH-SY5Y neuroblastoma cells expressing endogenous EP(1) receptors. Signalling pathway inhibitors were used to examine the roles of Rho, PKA, the cAMP response element binding protein (CREB) and NF-κB on the PGE(2) stimulated up-regulation of Nurr1. CREB and NF-κB signalling were also examined by immunoblot analysis and reporter gene assays. KEY RESULTS The EP(1) receptor mediated up-regulation of Nurr1 was blocked with inhibitors of Rho, PKA, NF-κB and CREB; but PGE(2) failed to significantly stimulate intracellular cAMP formation. PGE(2) stimulation of the EP1 receptor induced the phosphorylation and activation of CREB and NF-κB, which could be blocked by inhibition of PKA. CONCLUSIONS AND IMPLICATIONS PGE(2) stimulation of the human EP(1) receptor up-regulates the expression of Nurr1 by a mechanism involving the sequential activation of the Rho, PKA, CREB and NF-κB signalling pathways. EP(1) receptors are implicated in tumorigenesis and the up-regulation of Nurr1 may underlie the anti-apoptotic effects of PGE(2) .
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Affiliation(s)
- R Ji
- Department of Pharmacology & Toxicology, College of Pharmacy, The University of Arizona, Tucson, AZ, USA
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12
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Cotranslational cis-phosphorylation of the COOH-terminal tail is a key priming step in the maturation of cAMP-dependent protein kinase. Proc Natl Acad Sci U S A 2012; 109:E1221-9. [PMID: 22493239 DOI: 10.1073/pnas.1202741109] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
cAMP-dependent protein kinase A (PKA), ubiquitously expressed in mammalian cells, regulates a plethora of cellular processes through its ability to phosphorylate many protein substrates, including transcription factors, ion channels, apoptotic proteins, transporters, and metabolic enzymes. The PKA catalytic subunit has two phosphorylation sites, a well-studied site in the activation loop (Thr(197)) and another site in the C-terminal tail (Ser(338)) for which the role of phosphorylation is unknown. We show here, using in vitro studies and experiments with S49 lymphoma cells, that cis-autophosphorylation of Ser(338) occurs cotranslationally, when PKA is associated with ribosomes and precedes posttranslational phosphorylation of the activation loop Thr(197). Ser(338) phoshorylation is not required for PKA activity or formation of the holoenzyme complex; however, it is critical for processing and maturation of PKA, and it is a prerequisite for phosphorylation of Thr(197). After Thr(197) and Ser(338) are phosphorylated, both sites are remarkably resistant to phosphatases. Phosphatase resistance of the activation loop, a unique feature of both PKA and PKG, reflects the distinct way that signal transduction dynamics are controlled by cyclic nucleotide-dependent PKs.
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13
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Identification of Toxoplasma gondii cAMP dependent protein kinase and its role in the tachyzoite growth. PLoS One 2011; 6:e22492. [PMID: 21799871 PMCID: PMC3140512 DOI: 10.1371/journal.pone.0022492] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Accepted: 06/28/2011] [Indexed: 12/18/2022] Open
Abstract
Background cAMP-dependent protein kinase (PKA) has been implicated in the asexual stage of the Toxoplasma gondii life cycle through assaying the effect of a PKA-specific inhibitor on its growth rate. Since inhibition of the host cell PKA cannot be ruled out, a more precise evaluation of the role of PKA, as well as characterization of the kinase itself, is necessary. Methodology/Principal Finding The inhibitory effects of two PKA inhibitors, H89, an ATP-competitive chemical inhibitor, and PKI, a substrate-competitive mammalian natural peptide inhibitor, were estimated. In the in vitro kinase assay, the inhibitory effect of PKI on a recombinant T. gondii PKA catalytic subunit (TgPKA-C) was weaker compared to that on mammalian PKA-C. In a tachyzoite growth assay, PKI had little effect on the growth of tachyzoites, whereas H89 strongly inhibited it. Moreover, T. gondii PKA regulatory subunit (TgPKA-R)-overexpressing tachyzoites showed a significant growth defect. Conclusions/Significance Our data suggest that PKA plays an important role in the growth of tachyzoites, and the inhibitory effect of substrate-competitive inhibitor PKI on T. gondii PKA was low compared to that of the ATP competitive inhibitor H89.
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Dwivedi Y, Pandey GN. Elucidating biological risk factors in suicide: role of protein kinase A. Prog Neuropsychopharmacol Biol Psychiatry 2011; 35:831-41. [PMID: 20817068 PMCID: PMC3026860 DOI: 10.1016/j.pnpbp.2010.08.025] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/18/2010] [Revised: 08/17/2010] [Accepted: 08/26/2010] [Indexed: 01/19/2023]
Abstract
Suicide is a major public health concern. Although there have been several studies of suicidal behavior that focused on the roles of psychosocial and sociocultural factors, these factors are of too little predictive value to be clinically useful. Therefore, research on the biological perspective of suicide has gained a stronghold and appears to provide a promising approach to identify biological risk factors associated with suicidal behavior. Recent studies demonstrate that an alteration in synaptic and structural plasticity is key to affective illnesses and suicide. Signal transduction molecules play an important role in such plastic events. Protein kinase A (PKA) is a crucial enzyme in the adenylyl cyclase signal transduction pathway and is involved in regulating gene transcription, cell survival, and plasticity. In this review, we critically and comprehensively discuss the role of PKA in suicidal behavior. Because stress is an important component of suicide, we also discuss whether stress affects PKA and how this may be associated with suicidal behavior. In addition, we also discuss the functional significance of the findings regarding PKA by describing the role of important PKA substrates (i.e., Rap1, cyclic adenosine monophosphate response element binding protein, and target gene brain-derived neurotrophic factor). These studies suggest the interesting possibility that PKA and related signaling molecules may serve as important neurobiological factors in suicide and may be relevant in target-specific therapeutic interventions for these disorders.
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Affiliation(s)
- Yogesh Dwivedi
- The Psychiatric Institute, Department of Psychiatry, University of Illinois at Chicago, 1601 West Taylor Street, Chicago, IL 60612, USA.
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15
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Huttlin EL, Jedrychowski MP, Elias JE, Goswami T, Rad R, Beausoleil SA, Villén J, Haas W, Sowa ME, Gygi SP. A tissue-specific atlas of mouse protein phosphorylation and expression. Cell 2011; 143:1174-89. [PMID: 21183079 DOI: 10.1016/j.cell.2010.12.001] [Citation(s) in RCA: 1369] [Impact Index Per Article: 105.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2010] [Revised: 09/08/2010] [Accepted: 12/01/2010] [Indexed: 01/07/2023]
Abstract
Although most tissues in an organism are genetically identical, the biochemistry of each is optimized to fulfill its unique physiological roles, with important consequences for human health and disease. Each tissue's unique physiology requires tightly regulated gene and protein expression coordinated by specialized, phosphorylation-dependent intracellular signaling. To better understand the role of phosphorylation in maintenance of physiological differences among tissues, we performed proteomic and phosphoproteomic characterizations of nine mouse tissues. We identified 12,039 proteins, including 6296 phosphoproteins harboring nearly 36,000 phosphorylation sites. Comparing protein abundances and phosphorylation levels revealed specialized, interconnected phosphorylation networks within each tissue while suggesting that many proteins are regulated by phosphorylation independently of their expression. Our data suggest that the "typical" phosphoprotein is widely expressed yet displays variable, often tissue-specific phosphorylation that tunes protein activity to the specific needs of each tissue. We offer this dataset as an online resource for the biological research community.
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Affiliation(s)
- Edward L Huttlin
- Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA
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16
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cAMP initiates early phase neuron-like morphology changes and late phase neural differentiation in mesenchymal stem cells. Cell Mol Life Sci 2010; 68:863-76. [PMID: 20725762 DOI: 10.1007/s00018-010-0497-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2010] [Revised: 07/22/2010] [Accepted: 08/04/2010] [Indexed: 12/17/2022]
Abstract
The intracellular second messenger cAMP is frequently used in induction media to induce mesenchymal stem cells (MSCs) into neural lineage cells. To date, an understanding of the role cAMP exerts on MSCs and whether cAMP can induce MSCs into functional neurons is still lacking. We found cAMP initiated neuron-like morphology changes early and neural differentiation much later. The early phase changes in morphology were due to cell shrinkage, which subsequently rendered some cells apoptotic. While the morphology changes occurred prior to the expression of neural markers, it is not required for neural marker expression and the two processes are differentially regulated downstream of cAMP-activated protein kinase A. cAMP enabled MSCs to gain neural marker expressions with neuronal function, such as, calcium rise in response to neuronal activators, dopamine, glutamate, and potassium chloride. However, only some of the cells induced by cAMP responded to the three neuronal activators and further lack the neuronal morphology, suggesting that although cAMP is able to direct MSCs towards neural differentiation, they do not achieve terminal differentiation.
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17
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Leykauf K, Treeck M, Gilson PR, Nebl T, Braulke T, Cowman AF, Gilberger TW, Crabb BS. Protein kinase a dependent phosphorylation of apical membrane antigen 1 plays an important role in erythrocyte invasion by the malaria parasite. PLoS Pathog 2010; 6:e1000941. [PMID: 20532217 PMCID: PMC2880582 DOI: 10.1371/journal.ppat.1000941] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2009] [Accepted: 05/05/2010] [Indexed: 11/19/2022] Open
Abstract
Apicomplexan parasites are obligate intracellular parasites that infect a variety of hosts, causing significant diseases in livestock and humans. The invasive forms of the parasites invade their host cells by gliding motility, an active process driven by parasite adhesion proteins and molecular motors. A crucial point during host cell invasion is the formation of a ring-shaped area of intimate contact between the parasite and the host known as a tight junction. As the invasive zoite propels itself into the host-cell, the junction moves down the length of the parasite. This process must be tightly regulated and signalling is likely to play a role in this event. One crucial protein for tight-junction formation is the apical membrane antigen 1 (AMA1). Here we have investigated the phosphorylation status of this key player in the invasion process in the human malaria parasite Plasmodium falciparum. We show that the cytoplasmic tail of P. falciparum AMA1 is phosphorylated at serine 610. We provide evidence that the enzyme responsible for serine 610 phosphorylation is the cAMP regulated protein kinase A (PfPKA). Importantly, mutation of AMA1 serine 610 to alanine abrogates phosphorylation of AMA1 in vivo and dramatically impedes invasion. In addition to shedding unexpected new light on AMA1 function, this work represents the first time PKA has been implicated in merozoite invasion.
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Affiliation(s)
- Kerstin Leykauf
- Macfarlane Burnet Institute for Medical Research & Public Health, Melbourne, Victoria, Australia
| | - Moritz Treeck
- Bernhard Nocht Institute for Tropical Medicine, Department of Molecular Parasitology, Hamburg, Germany
| | - Paul R. Gilson
- Macfarlane Burnet Institute for Medical Research & Public Health, Melbourne, Victoria, Australia
| | - Thomas Nebl
- Walter & Eliza Hall Institute of Medical Research, Melbourne, Victoria, Australia
| | - Thomas Braulke
- Department of Biochemistry, Children's Hospital, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Alan F. Cowman
- Walter & Eliza Hall Institute of Medical Research, Melbourne, Victoria, Australia
| | - Tim W. Gilberger
- Bernhard Nocht Institute for Tropical Medicine, Department of Molecular Parasitology, Hamburg, Germany
- M.G. DeGroote Institute for Infectious Disease Research, McMaster University, Hamilton, Ontario, Canada
| | - Brendan S. Crabb
- Macfarlane Burnet Institute for Medical Research & Public Health, Melbourne, Victoria, Australia
- The University of Melbourne, Victoria, Australia
- Monash University, Victoria, Australia
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18
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Steichen JM, Iyer GH, Li S, Saldanha SA, Deal MS, Woods VL, Taylor SS. Global consequences of activation loop phosphorylation on protein kinase A. J Biol Chem 2009; 285:3825-3832. [PMID: 19965870 PMCID: PMC2823524 DOI: 10.1074/jbc.m109.061820] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Phosphorylation of the activation loop is one of the most common mechanisms for regulating protein kinase activity. The catalytic subunit of cAMP-dependent protein kinase autophosphorylates Thr(197) in the activation loop when expressed in Escherichia coli. Although mutation of Arg(194) to Ala prevents autophosphorylation, phosphorylation of Thr(197) can still be achieved by a heterologous protein kinase, phosphoinositide-dependent protein kinase (PDK1), in vitro. In this study, we examined the structural and functional consequences of adding a single phosphate to the activation loop of cAMP-dependent protein kinase by comparing the wild type C-subunit to the R194A mutant either in the presence or the absence of activation loop phosphorylation. Phosphorylation of Thr(197) decreased the K(m) by approximately 15- and 7-fold for kemptide and ATP, respectively, increased the stability of the enzyme as measured by fluorescence and circular dichroism, and enhanced the binding between the C-subunit and IP20, a protein kinase inhibitor peptide. Additionally, deuterium exchange coupled to mass spectrometry was used to compare the structural dynamics of these proteins. All of the regions of the C-subunit analyzed underwent amide hydrogen exchange at a higher or equal rate in the unphosphorylated enzyme compared with the phosphorylated enzyme. The largest changes occurred at the C terminus of the activation segment in the p + 1 loop/APE regions and the alphaH-alphaI loop motifs and leads to the prediction of a coordinated phosphorylation-induced salt bridge between two conserved residues, Glu(208) and Arg(280).
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Affiliation(s)
- Jon M Steichen
- From the Departments of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093
| | - Ganesh H Iyer
- From the Departments of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093
| | - Sheng Li
- the Department of Medicine and Biomedical Sciences Graduate Program, University of California, San Diego, La Jolla, California 92093
| | - S Adrian Saldanha
- From the Departments of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093
| | - Michael S Deal
- From the Departments of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093
| | - Virgil L Woods
- the Department of Medicine and Biomedical Sciences Graduate Program, University of California, San Diego, La Jolla, California 92093
| | - Susan S Taylor
- From the Departments of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093; Departments of Pharmacology, University of California, San Diego, La Jolla, California 92093; the Departments of Howard Hughes Medical Institute, University of California, San Diego, La Jolla, California 92093.
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19
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Ligand-induced global transitions in the catalytic domain of protein kinase A. Proc Natl Acad Sci U S A 2009; 106:3023-8. [PMID: 19204278 DOI: 10.1073/pnas.0813266106] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Conformational transitions play a central role in the phosphorylation mechanisms of protein kinase. To understand the nature of these transitions, we investigated the dynamics of nucleotide binding to the catalytic domain of PKA, a prototype for the protein kinase enzyme family. The open-to-closed transition in PKA was constructed as a function of ATP association by using available X-ray data and Brownian dynamics. Analyzing the multiple kinetic trajectories at the residue level, we find that the spatial rearrangement of the residues around the nucleotide-binding pocket, along with suppressed local fluctuations, controls the compaction of the entire molecule. In addition, to accommodate the stresses induced by ATP binding at the early transition stage, partial unfoldings (cracking) and reformations of several native contacts occur at the interfaces between the secondary structure motifs enveloping the binding pocket. This suggests that the enzyme experiences local structural deformations while reaching its functional, ATP-bound state. Our dynamical view of the ligand-induced transitions in PKA suggests that the kinetic hierarchy of local and global dynamics, the variable fluctuation of residues and the necessity of partial local unfolding may be fundamental components in other large scale allosteric transitions.
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20
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Cheng X, Ji Z, Tsalkova T, Mei F. Epac and PKA: a tale of two intracellular cAMP receptors. Acta Biochim Biophys Sin (Shanghai) 2008; 40:651-62. [PMID: 18604457 PMCID: PMC2630796 DOI: 10.1111/j.1745-7270.2008.00438.x] [Citation(s) in RCA: 269] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
cAMP-mediated signaling pathways regulate a multitude of important biological processes under both physiological and pathological conditions, including diabetes, heart failure and cancer. In eukaryotic cells, the effects of cAMP are mediated by two ubiquitously expressed intracellular cAMP receptors, the classic protein kinase A (PKA)/cAMP-dependent protein kinase and the recently discovered exchange protein directly activated by camp (Epac)/cAMP-regulated guanine nucleotide exchange factors. Like PKA, Epac contains an evolutionally conserved cAMP binding domain that acts as a molecular switch for sensing intracellular second messenger cAMP levels to control diverse biological functions. The existence of two families of cAMP effectors provides a mechanism for a more precise and integrated control of the cAMP signaling pathways in a spatial and temporal manner. Depending upon the specific cellular environments as well as their relative abundance, distribution and localization, Epac and PKA may act independently, converge synergistically or oppose each other in regulating a specific cellular function.
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Affiliation(s)
- Xiaodong Cheng
- Department of Pharmacology and Toxicology, Sealy Center for Cancer Cell Biology, University of Texas Medical Branch, Galveston, Texas 77555-1031, USA.
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21
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Transient hypoxia stimulates mitochondrial biogenesis in brain subcortex by a neuronal nitric oxide synthase-dependent mechanism. J Neurosci 2008; 28:2015-24. [PMID: 18305236 DOI: 10.1523/jneurosci.5654-07.2008] [Citation(s) in RCA: 142] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The adaptive mechanisms that protect brain metabolism during and after hypoxia, for instance, during hypoxic preconditioning, are coordinated in part by nitric oxide (NO). We tested the hypothesis that acute transient hypoxia stimulates NO synthase (NOS)-activated mechanisms of mitochondrial biogenesis in the hypoxia-sensitive subcortex of wild-type (Wt) and neuronal NOS (nNOS) and endothelial NOS (eNOS)-deficient mice. Mice were exposed to hypobaric hypoxia for 6 h, and changes in immediate hypoxic transcriptional regulation of mitochondrial biogenesis was assessed in relation to mitochondrial DNA (mtDNA) content and mitochondrial density. There were no differences in cerebral blood flow or hippocampal PO2 responses to acute hypoxia among these strains of mice. In Wt mice, hypoxia increased mRNA levels for peroxisome proliferator-activated receptor-gamma coactivator-1alpha (PGC-1 alpha), nuclear respiratory factor-1, and mitochondrial transcription factor A. After 24 h, new mitochondria, localized in reporter mice expressing mitochondrial green fluorescence protein, were seen primarily in hippocampal neurons. eNOS-/- mice displayed lower basal levels but maintained hypoxic induction of these transcripts. In contrast, nuclear transcriptional regulation of mitochondrial biogenesis in nNOS-/- mice was normal at baseline but did not respond to hypoxia. After hypoxia, subcortical mtDNA content increased in Wt and eNOS-/- mice but not in nNOS-/- mice. Hypoxia stimulated PGC-1alpha protein expression and phosphorylation of protein kinase A and cAMP response element binding (CREB) protein in Wt mice, but CREB only was activated in eNOS-/- mice and not in nNOS-/- mice. These findings demonstrate that hypoxic preconditioning elicits subcortical mitochondrial biogenesis by a novel mechanism that requires nNOS regulation of PGC-1alpha and CREB.
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22
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Goentzel B, Weigel P, Steinberg R. Recombinant human hyaluronan synthase 3 is phosphorylated in mammalian cells. Biochem J 2006; 396:347-54. [PMID: 16522194 PMCID: PMC1462723 DOI: 10.1042/bj20051782] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Hyaluronan is a ubiquitous component of vertebrate extracellular and cell-associated matrices that serves as a key structural component of skin, cartilage, eyes and joints, and plays important roles in dynamic cellular processes, including embryogenesis, inflammation, wound healing and metastasis. Hyaluronan is synthesized by three homologous hyaluronan synthases designated HAS1, HAS2 and HAS3 that differ in their tissue distribution, regulation and enzymatic characteristics. Some progress has been made in characterizing regulation of HAS transcripts and in distinguishing the enzymatic properties of the various HAS isoforms, but essentially nothing is known about their possible regulation by posttranslational modification. Using [32P]P(i) radiolabelling of a recombinant FLAG (DYKDDDDK) epitope-tagged version of human HAS3 expressed in COS-7 cells, we show that HAS3 is serine-phosphorylated and that this phosphorylation can be enhanced by a number of effectors--most significantly by a membrane-permeable analogue of cAMP. By employing a novel FLAG-tagged phosphorylated reference protein derived from EGFP (enhanced green fluorescent protein), we were able to estimate the stoichiometry of FLAG-HAS3 phosphorylation. It was approx. 0.11 in unstimulated cells and increased to as much as 0.32 in cells stimulated with 8-(4-chlorophenylthio)-cAMP.
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Affiliation(s)
- Brian J. Goentzel
- Department of Biochemistry and Molecular Biology, the University of Oklahoma Health Sciences Center, Oklahoma City, OK 73190, U.S.A
| | - Paul H. Weigel
- Department of Biochemistry and Molecular Biology, the University of Oklahoma Health Sciences Center, Oklahoma City, OK 73190, U.S.A
| | - Robert A. Steinberg
- Department of Biochemistry and Molecular Biology, the University of Oklahoma Health Sciences Center, Oklahoma City, OK 73190, U.S.A
- To whom correspondence should be addressed (email )
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Saito R, Tabata Y, Muto A, Arai KI, Watanabe S. Melk-like kinase plays a role in hematopoiesis in the zebra fish. Mol Cell Biol 2005; 25:6682-93. [PMID: 16024803 PMCID: PMC1190327 DOI: 10.1128/mcb.25.15.6682-6693.2005] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A serine/threonine kinase, Melk, was initially cloned in mouse oocytes as a maternal gene, but whose function was unknown. In adult mice, Melk was strongly expressed in the thymus and bone marrow, suggesting a role for Melk in hematopoiesis. We cloned a Melk-like gene from zebra fish (zMelk). zMelk-like gene was expressed in the brain and lateral mesoderm at 12 hours postfertilization (hpf) and in several tissues of adult fish, including the kidney and spleen, both of which are known to be hematopoietic tissues in zebra fish. Abrogation of zMelk-like gene function by zMelk-like gene-specific Morpholino (MO) resulted in abnormal swelling around the tectum region. In addition, the start of blood circulation was severely delayed but, in contrast, the vessel formation seemed normal. Expression of scl, gata-1, and lmo-2 was down regulated at 12 to 14 hpf in the zMelk-like gene MO-injected embryos, and the coexpression of gata-1 rescued the anemic phenotype induced by zMelk-like gene MO. Expression of the zMelk-like gene in embryos enhanced gata-1 promoter-dependent enhanced green fluorescent protein expression, suggesting that the zMelk-like gene affects gata-1 expression at the transcriptional level. Taken together, our data suggest that the zMelk-like gene may play a role in primitive hematopoiesis by affecting the expression of genes critical for hematopoiesis.
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Affiliation(s)
- Rika Saito
- Institute of Medical Science, University of Tokyo, Department of Molecular and Developmental Biology, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan
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24
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Tang Y, McLeod M. In vivo activation of protein kinase A in Schizosaccharomyces pombe requires threonine phosphorylation at its activation loop and is dependent on PDK1. Genetics 2005; 168:1843-53. [PMID: 15611161 PMCID: PMC1448717 DOI: 10.1534/genetics.104.032466] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Phosphoinositide-dependent protein kinase 1 (PDK1) plays a central role in cellular signaling by phosphorylating members of the AGC family of kinases. This family includes protein kinase C (PKC), protein kinase B (PKB), p70/p90 ribosomal S6 kinases (RSK and S6K), and the catalytic subunit of cAMP-dependent protein kinase (PKA). Although PDK1 phosphorylates and activates PKC, PKB, and RSK in vivo, PDK1 regulation of PKA remains controversial. We isolated ksg1, the fission yeast ortholog of mammalian PDK1, as a suppressor of growth defects caused by loss of the stress-activated MAP kinase, Spc1. Here, we demonstrate that Ksg1 is required for activation of PKA. Cells containing the ksg1.12 thermolabile allele exhibit pleiotropic phenotypes, including the failure to arrest in G(1) and an inability to conjugate. The ksg1.12 allele strongly suppresses defects associated with unregulated PKA. Pka1, the catalytic subunit of cAMP-dependent protein kinase, is phosphorylated in vivo at Thr-356, which is located in the activation loop of the kinase and corresponds to Thr-197 in mammalian PKA. Phosphorylation of Thr-356 is required for in vivo activation of Pka1 and is dependent upon Ksg1. These data provide experimental evidence that PKA is a physiological substrate for PDK1.
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Affiliation(s)
- Yi Tang
- Department of Microbiology and Immunology, State University of New York Downstate Medical Center, Brooklyn, New York 11203-2098, USA
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Wang ZX, Wu JW. Autophosphorylation kinetics of protein kinases. Biochem J 2002; 368:947-52. [PMID: 12190618 PMCID: PMC1223023 DOI: 10.1042/bj20020557] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2002] [Revised: 07/29/2002] [Accepted: 08/22/2002] [Indexed: 11/17/2022]
Abstract
Protein kinases play a central role in cellular signal transduction, by transmitting biochemical information between activated membrane-bound receptors and physiological target proteins. In addition to phosphorylating other proteins, almost all protein kinases catalyse autophosphorylation reactions (i.e. reactions in which the kinase serves as its own substrate). The autophosphorylation reactions can be intramolecular or intermolecular. In the present study, a detailed kinetic analysis of the intermolecular autophosphorylation reaction is presented. On the basis of the kinetic equations, a new procedure is developed to evaluate the kinetic parameters of the autophosphorylation reaction. This method was used to analyse the intermolecular autophosphorylation of an S6/H4 kinase from human placenta. At a fixed ATP concentration of 0.125 mM, the apparent catalytic-centre activity (turnover number; k (cat)) and apparent Michaelis-Menten constant ( K (m)) for the autophosphorylation reaction were determined to be 0.91 min(-1) and 0.86 microM respectively.
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Affiliation(s)
- Zhi-Xin Wang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Academia Sinica, Beijing 100101, P.R. China.
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26
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Facchin S, Lopreiato R, Stocchetto S, Arrigoni G, Cesaro L, Marin O, Carignani G, Pinna LA. Structure-function analysis of yeast piD261/Bud32, an atypical protein kinase essential for normal cell life. Biochem J 2002; 364:457-63. [PMID: 12023889 PMCID: PMC1222591 DOI: 10.1042/bj20011376] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The Saccharomyces cerevisiae YGR262c/BUD32 gene, whose disruption causes a severe pleiotropic phenotype, encodes a 261-residue putative protein kinase, piD261, whose structural homologues have been identified in a variety of organisms, including humans, and whose function is unknown. We have demonstrated previously that piD261, expressed in Escherichia coli as a recombinant protein, is a Ser/Thr kinase, as judged by its ability to autophosphorylate and to phosphorylate casein. Here we describe a mutational analysis showing that, despite low sequence similarity, the invariant residues representing the signature of protein kinases are conserved in piD261 and in its structural homologues, but are embedded in an altered context, suggestive of unique mechanistic properties. Especially noteworthy are: (i) three unique inserts of unknown function within the N-terminal lobe, (ii) the lack of a lysyl residue which in all other Ser/Thr kinases participates in the catalytic event by interacting with the transferred ATP gamma-phosphate, and which in piD261 is replaced by a threonine, and (iii) an exceedingly short activation loop including two serines, Ser-187 and Ser-189, whose autophosphorylation accounts for the appearance of an upshifted band upon SDS/PAGE. A mutant in which these serines are replaced by alanines was devoid of the upshifted band and displayed reduced catalytic activity. This would include piD261 in the category of protein kinases activated by phosphorylation, although it lacks the RD (Arg-Asp) motif which is typical of these enzymes.
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Affiliation(s)
- Sonia Facchin
- Dipartimento di Chimica Biologica, Centro Studi delle Biomembrane del Consiglio Nazionale delle Ricerche and Centro Ricerca Interdipartimentale Biotecnologie Innovative, University of Padova, Viale G. Colombo, 3, 35125 Padova, Italy
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27
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Thullner S, Gesellchen F, Wiemann S, Pyerin W, Kinzel V, Bossemeyer D. The protein kinase A catalytic subunit Cbeta2: molecular characterization and distribution of the splice variant. Biochem J 2000; 351:123-32. [PMID: 10998354 PMCID: PMC1221342 DOI: 10.1042/0264-6021:3510123] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Cbeta2, a 46 kDa splice variant of the Cbeta isoform, is the largest isoform so far described for catalytic subunits from cAMP-dependent protein kinase in mammals. It differs from Cbeta in the first 15 N-terminal residues which are replaced with a 62-residue domain with no similarity to other known proteins. The Cbeta2 protein was identified in cardiac tissue by MS, microsequencing and C-subunit-isoform-selective antibodies. The Cbeta2 protein has a very low abundance of about 2% of total affinity-purified C subunits from bovine cardiac tissue. This, and the similarity of its biochemical properties to Calpha and Cbeta, are probably some of the reasons why the Cbeta2 protein has escaped detection so far. The abundance of the Cbeta2 protein differs dramatically between tissues, with most protein detected in heart, liver and spleen, and the lowest level in testis. Cbeta2 protein shows kinase activity against synthetic substrates, and is inhibited by the protein kinase inhibitor peptide PKI(5-24). The degree of Cbeta2 removal from tissue extracts by binding to PKI(5-24) depends on the cAMP level, i.e. on the dissociation state of the holoenzyme. Two sites in the protein are phosphorylated: Thr-244 in the activation segment and Ser-385 close to the C-terminus. By affinity purification and immunodetection Cbeta2 was found in cattle, pig, rat, mouse and turkey tissue and in HeLa cells. In the cAMP-insensitive CHO 10260 cell line, which has normal Cbeta but is depleted of Calpha, stable transfection with Cbeta2 restored most of the cAMP-induced morphological changes. Cbeta2 is a ubiquitously expressed protein with characteristic properties of a cAMP-dependent protein kinase catalytic subunit.
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Affiliation(s)
- S Thullner
- Department of Pathochemistry, German Cancer Research Center, DKFZ, INF 280, D-69120 Heidelberg, Germany
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28
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Cheng X, Ma Y, Moore M, Hemmings BA, Taylor SS. Phosphorylation and activation of cAMP-dependent protein kinase by phosphoinositide-dependent protein kinase. Proc Natl Acad Sci U S A 1998; 95:9849-54. [PMID: 9707564 PMCID: PMC21425 DOI: 10.1073/pnas.95.17.9849] [Citation(s) in RCA: 170] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Although phosphorylation of Thr-197 in the activation loop of the catalytic subunit of cAMP-dependent protein kinase (PKA) is an essential step for its proper biological function, the kinase responsible for this reaction in vivo has remained elusive. Using nonphosphorylated recombinant catalytic subunit as a substrate, we have shown that the phosphoinositide-dependent protein kinase, PDK1, expressed in 293 cells, phosphorylates and activates the catalytic subunit of PKA. The phosphorylation of PKA by PDK1 is rapid and is insensitive to PKI, the highly specific heat-stable protein kinase inhibitor. A mutant form of the catalytic subunit where Thr-197 was replaced with Asp was not a substrate for PDK1. In addition, phosphorylation of the catalytic subunit can be monitored immunochemically by using antibodies that recognize Thr-197 phosphorylated enzyme but not unphosphorylated enzyme or the Thr197Asp mutant. PDK1, or one of its homologs, is thus a likely candidate for the in vivo PKA kinase that phosphorylates Thr-197. This finding opens a new dimension in our thinking about this ubiquitous protein kinase and how it is regulated in the cell.
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Affiliation(s)
- X Cheng
- Howard Hughes Medical Institute, Department of Chemistry and Biochemistry, University of California at San Diego, La Jolla, CA 92093-0654, USA
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29
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Yu JS, Chen WJ, Ni MH, Chan WH, Yang SD. Identification of the regulatory autophosphorylation site of autophosphorylation-dependent protein kinase (auto-kinase). Evidence that auto-kinase belongs to a member of the p21-activated kinase family. Biochem J 1998; 334 ( Pt 1):121-31. [PMID: 9693111 PMCID: PMC1219670 DOI: 10.1042/bj3340121] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Autophosphorylation-dependent protein kinase (auto-kinase) was identified from pig brain and liver on the basis of its unique autophosphorylation/activation property [Yang, Fong, Yu and Liu (1987) J. Biol. Chem. 262, 7034-7040; Yang, Chang and Soderling (1987) J. Biol. Chem. 262, 9421-9427]. Its substrate consensus sequence motif was determined as being -R-X-(X)-S*/T*-X3-S/T-. To characterize auto-kinase further, we partly sequenced the kinase purified from pig liver. The N-terminal sequence (VDGGAKTSDKQKKKAXMTDE) and two internal peptide sequences (EKLRTIV and LQNPEK/ILTP/FI) of auto-kinase were obtained. These sequences identify auto-kinase as a C-terminal catalytic fragment of p21-activated protein kinase 2 (PAK2 or gamma-PAK) lacking its N-terminal regulatory region. Auto-kinase can be recognized by an antibody raised against the C-terminal peptide of human PAK2 by immunoblotting. Furthermore the autophosphorylation site sequence of auto-kinase was successfully predicted on the basis of its substrate consensus sequence motif and the known PAK2 sequence, and was further demonstrated to be RST(P)MVGTPYWMAPEVVTR by phosphoamino acid analysis, manual Edman degradation and phosphopeptide mapping via the help of phosphorylation site analysis of a synthetic peptide corresponding to the sequence of PAK2 from residues 396 to 418. During the activation process, auto-kinase autophosphorylates mainly on a single threonine residue Thr402 (according to the sequence numbering of human PAK2). In addition, a phospho-specific antibody against a synthetic phosphopeptide containing this identified sequence was generated and shown to be able to differentially recognize the activated auto-kinase autophosphorylated at Thr402 but not the non-phosphorylated/inactive auto-kinase. Immunoblot analysis with this phospho-specific antibody further revealed that the change in phosphorylation level of Thr402 of auto-kinase was well correlated with the activity change of the kinase during both autophosphorylation/activation and protein phosphatase-mediated dephosphorylation/inactivation processes. Taken together, our results identify Thr402 as the regulatory autophosphorylation site of auto-kinase, which is a C-terminal catalytic fragment of PAK2.
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Affiliation(s)
- J S Yu
- Department of Cell and Molecular Biology, Institute of Basic Medicine, Chang Gung University, Tao-Yuan, Taiwan, Republic of China.
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30
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Szczepanowska J, Ramachandran U, Herring CJ, Gruschus JM, Qin J, Korn ED, Brzeska H. Effect of mutating the regulatory phosphoserine and conserved threonine on the activity of the expressed catalytic domain of Acanthamoeba myosin I heavy chain kinase. Proc Natl Acad Sci U S A 1998; 95:4146-51. [PMID: 9539704 PMCID: PMC22456 DOI: 10.1073/pnas.95.8.4146] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Phosphorylation of Ser-627 is both necessary and sufficient for full activity of the expressed 35-kDa catalytic domain of myosin I heavy chain kinase (MIHCK). Ser-627 lies in the variable loop between highly conserved residues DFG and APE at a position at which a phosphorylated Ser/Thr also occurs in many other Ser/Thr protein kinases. The variable loop of MIHCK contains two other hydroxyamino acids: Thr-631, which is conserved in almost all Ser/Thr kinases, and Thr-632, which is not conserved. We determined the effects on the kinase activity of the expressed catalytic domain of mutating Ser-627, Thr-631, and Thr-632 individually to Ala, Asp, and Glu. The S627A mutant was substantially less active than wild type (wt), with a lower kcat and higher Km for both peptide substrate and ATP, but was more active than unphosphorylated wt. The S627D and S627E mutants were also less active than phosphorylated wt, i.e., acidic amino acids cannot substitute for phospho-Ser-627. The activity of the T631A mutant was as low as that of the S627A mutant, whereas the T632A mutant was as active as phosphorylated wt, indicating that highly conserved Thr-631, although not phosphorylated, is essential for catalytic activity. Asp and Glu substitutions for Thr-631 and Thr-632 were inhibitory to various degrees. Molecular modeling indicated that Thr-631 can hydrogen bond with conserved residue Asp-591 in the catalytic loop and that similar interactions are possible for other kinases whose activities also are regulated by phosphorylation in the variable loop. Thus, this conserved Thr residue may be essential for the activities of other Ser/Thr protein kinases as well as for the activity of MIHCK.
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Affiliation(s)
- J Szczepanowska
- Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892, USA
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31
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Cauthron RD, Carter KB, Liauw S, Steinberg RA. Physiological phosphorylation of protein kinase A at Thr-197 is by a protein kinase A kinase. Mol Cell Biol 1998; 18:1416-23. [PMID: 9488457 PMCID: PMC108855 DOI: 10.1128/mcb.18.3.1416] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Phosphorylation of the catalytic subunit of cyclic AMP-dependent protein kinase, or protein kinase A, on Thr-197 is required for optimal enzyme activity, and enzyme isolated from either animal sources or bacterial expression strains is found phosphorylated at this site. Autophosphorylation of Thr-197 occurs in Escherichia coli and in vitro but is an inefficient intermolecular reaction catalyzed primarily by active, previously phosphorylated molecules. In contrast, the Thr-197 phosphorylation of newly synthesized protein kinase A in intact S49 mouse lymphoma cells is both efficient and insensitive to activators or inhibitors of intracellular protein kinase A. Using [35S]methionine-labeled, nonphosphorylated, recombinant catalytic subunit as the substrate in a gel mobility shift assay, we have identified an activity in extracts of protein kinase A-deficient S49 cells that phosphorylates catalytic subunit on Thr-197. The protein kinase A kinase activity partially purified by anion-exchange and hydroxylapatite chromatography is an efficient catalyst of protein kinase A phosphorylation in terms of both a low Km for ATP and a rapid time course. Phosphorylation of wild-type catalytic subunit by the kinase kinase activates the subunit for binding to a pseudosubstrate peptide inhibitor of protein kinase A. By both the gel shift assay and a [gamma-32P]ATP incorporation assay, the enzyme is active on wild-type catalytic subunit and on an inactive mutant with Met substituted for Lys-72 but inactive on a mutant with Ala substituted for Thr-197. Combined with the results from mutant subunits, phosphoamino acid analysis suggests that the enzyme is specific for phosphorylation of Thr-197.
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Affiliation(s)
- R D Cauthron
- Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City 73190, USA
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32
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Wang HY, Lin W, Dyck JA, Yeakley JM, Songyang Z, Cantley LC, Fu XD. SRPK2: a differentially expressed SR protein-specific kinase involved in mediating the interaction and localization of pre-mRNA splicing factors in mammalian cells. J Cell Biol 1998; 140:737-50. [PMID: 9472028 PMCID: PMC2141757 DOI: 10.1083/jcb.140.4.737] [Citation(s) in RCA: 239] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Reversible phosphorylation plays an important role in pre-mRNA splicing in mammalian cells. Two kinases, SR protein-specific kinase (SRPK1) and Clk/Sty, have been shown to phosphorylate the SR family of splicing factors. We report here the cloning and characterization of SRPK2, which is highly related to SRPK1 in sequence, kinase activity, and substrate specificity. Random peptide selection for preferred phosphorylation sites revealed a stringent preference of SRPK2 for SR dipeptides, and the consensus derived may be used to predict potential phosphorylation sites in candidate arginine and serine-rich (RS) domain-containing proteins. Phosphorylation of an SR protein (ASF/SF2) by either SRPK1 or 2 enhanced its interaction with another RS domain-containing protein (U1 70K), and overexpression of either kinase induced specific redistribution of splicing factors in the nucleus. These observations likely reflect the function of the SRPK family of kinases in spliceosome assembly and in mediating the trafficking of splicing factors in mammalian cells. The biochemical and functional similarities between SRPK1 and 2, however, are in contrast to their differences in expression. SRPK1 is highly expressed in pancreas, whereas SRPK2 is highly expressed in brain, although both are coexpressed in other human tissues and in many experimental cell lines. Interestingly, SRPK2 also contains a proline-rich sequence at its NH2 terminus, and a recent study showed that this NH2-terminal sequence has the capacity to interact with a WW domain protein in vitro. Together, our studies suggest that different SRPK family members may be uniquely regulated and targeted, thereby contributing to splicing regulation in different tissues, during development, or in response to signaling.
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Affiliation(s)
- H Y Wang
- Division of Cellular and Molecular Medicine, Department of Medicine, University of California, San Diego, La Jolla, California 92093-0651, USA
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33
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Abstract
Great progress has recently been made in our understanding of the regulation of the eukaryotic cell cycle, and the central role of cyclin-dependent kinases is now clear. In Aspergillus nidulans it has been established that a second class of cell-cycle-regulated protein kinases, typified by NIMA (encoded by the nimA gene), is also required for cell cycle progression into mitosis. Indeed, both p34cdc2/cyclin B and NIMA have to be correctly activated before mitosis can be initiated in this species, and p34cdc2/cyclin B plays a role in the mitosis-specific activation of NIMA. In addition, both kinases have to be proteolytically destroyed before mitosis can be completed. NIMA-related kinases may also regulate the cell cycle in other eukaryotes, as expression of NIMA can promote mitotic events in yeast, frog or human cells. Moreover, dominant-negative versions of NIMA can adversely affect the progression of human cells into mitosis, as they do in A. nidulans. The ability of NIMA to influence mitotic regulation in human and frog cells strongly suggests the existence of a NIMA pathway of mitotic regulation in higher eukaryotes. A growing number of NIMA-related kinases have been isolated from organisms ranging from fungi to humans, and some of these kinases are also cell-cycle-regulated. How NIMA-related kinases and cyclin-dependent kinases act in concert to promote cell cycle transitions is just beginning to be understood. This understanding is the key to a full knowledge of cell cycle regulation.
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Affiliation(s)
- S A Osmani
- Weis Center for Research, Geisinger Clinic, Danville, PA 17822-2617, USA
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34
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Timms JF, Noble ME, Gregoriou M. An investigation of the role of Glu-842, Glu-844 and His-846 in the function of the cytoplasmic domain of the epidermal growth factor receptor. Biochem J 1995; 308 ( Pt 1):219-29. [PMID: 7755568 PMCID: PMC1136866 DOI: 10.1042/bj3080219] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Activation of several protein kinases is mediated, at least in part, by phosphorylation of conserved Thr or Tyr residues located in a variable loop region, near the active site. In certain kinases, this activation loop also controls access of peptide substrates to the active site. In the corresponding region of the epidermal growth factor (EGF) receptor, a potential phosphorylation site, Tyr-845, does not appear to have a major regulatory role. In order to find out whether this variable loop can modulate the peptide phosphorylation and self-phosphorylation activities of the EGF receptor kinase, we investigated the role of residues around Tyr-845, using site-directed mutagenesis. Multiple sequence alignment showed that residues Glu-842, Glu-844 and His-846 are conserved or nearly conserved in eight members of the EGF receptor family. Mutants Glu-842-->Ser, Glu-844-->Gln and His-846-->Ala were expressed in the baculovirus/insect cell system, purified to near-homogeneity and characterized with respect to their peptide phosphorylation and self-phosphorylation activities. All three mutants were active, and these changes did not affect ATP binding directly. However, all mutations increased the Km(app.) for peptide substrates and MnATP in peptide phosphorylation reactions. The Vmax. for the phosphorylation of peptide RREELQDDYEDD was unaltered, but the Vmax. for self-phosphorylation (with variable [MnATP]) decreased 4-, 2- and 7-fold for mutants Glu-842-->Ser, Glu-844-->Gln and His-846-->Ala respectively, compared with the wild-type. These results suggest that binding of this peptide restored an optimal conformation at the active site that might be impaired by the mutations. A study of the dependence of initial rates of self-phosphorylation on cytoplasmic domain concentration showed that the order of reaction increased with the progress of self-phosphorylation. Both pre-phosphorylation and high concentrations of ammonium sulphate restored maximal or near-maximal levels of self-phosphorylation in the mutants, possibly through compensating conformational changes. A plausible homology model, based on the cyclic AMP-dependent protein kinase catalytic subunit, accommodated the sequence Glu-841-Glu-Lys-Glu as an insertion in the peptide binding loop at the edge of the active site cleft. The model suggests that Glu-844 and His-846 may participate in H-bonding interactions, thus stabilizing the active site region, while Glu-842 does not appear to interact with regions of the catalytic core.
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Affiliation(s)
- J F Timms
- Department of Biochemistry, University of Oxford, U.K
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35
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Calalb MB, Polte TR, Hanks SK. Tyrosine phosphorylation of focal adhesion kinase at sites in the catalytic domain regulates kinase activity: a role for Src family kinases. Mol Cell Biol 1995; 15:954-63. [PMID: 7529876 PMCID: PMC231984 DOI: 10.1128/mcb.15.2.954] [Citation(s) in RCA: 770] [Impact Index Per Article: 26.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Focal adhesion kinase (FAK) is a widely expressed nonreceptor protein-tyrosine kinase implicated in integrin-mediated signal transduction pathways and in the process of oncogenic transformation by v-Src. Elevation of FAK's phosphotyrosine content, following both cell adhesion to extracellular matrix substrata and cell transformation by Rous sarcoma virus, correlates directly with an increased kinase activity. To help elucidate the role of FAK phosphorylation in signal transduction events, we used a tryptic phosphopeptide mapping approach to identify tyrosine sites of phosphorylation responsive to both cell adhesion and Src transformation. We have identified four tyrosines, 397, 407, 576, and 577, which are phosphorylated in mouse BALB/3T3 fibroblasts in an adhesion-dependent manner. Tyrosine 397 has been previously recognized as the major site of FAK autophosphorylation. Phosphorylation of tyrosines 407, 576, and 577, which are previously unrecognized sites, is significantly elevated in the presence of c-Src in vitro and v-Src in vivo. Tyrosines 576 and 577 lie within catalytic subdomain VIII--a region recognized as a target for phosphorylation-mediated regulation of protein kinase activity. We found that maximal kinase activity of FAK immune complexes requires phosphorylation of both tyrosines 576 and 577. Our results indicate that phosphorylation of FAK by Src (or other Src family kinases) is an important step in the formation of an active signaling complex.
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Affiliation(s)
- M B Calalb
- Department of Cell Biology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232
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36
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Glazer RI, Rohlff C. Transcriptional regulation of multidrug resistance in breast cancer. Breast Cancer Res Treat 1994; 31:263-71. [PMID: 7881104 DOI: 10.1007/bf00666159] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The development of cross-resistance to many natural product anticancer drugs, termed multidrug resistance (MDR), is one of the major reasons why cancer chemotherapy ultimately fails. This type of MDR is often associated with over-expression of the MDR1 gene product, P-glycoprotein (Pgp), a multifunctional drug transporter. The expression of MDR in breast tumors is related to their origination from a tissue that constitutively expresses Pgp as well as to the development of resistance during successive courses of chemotherapy. Therefore, understanding the mechanisms that regulate the transcriptional activation of MDR1 may afford a means of reducing or eliminating MDR. We have found that MDR1 expression can be modulated by type I cAMP-dependent protein kinase (PKA), opening up the possibility of modulating MDR by selectively down-regulating the activity of PKA-dependent transcription factors which upregulate MDR1 expression. High levels of type I PKA occurs in primary breast carcinomas and patients exhibiting this phenotype show decreased survival. The selective type I cAMP-dependent protein kinase (PKA) inhibitors, 8-Cl-cAMP and Rp8-Cl-cAMP[S] may be particularly useful for downregulating PKA-dependent MDR-associated transcription factors, and we have found these compounds to downregulate transient expression of a reporter gene under the control of several MDR1 promoter elements. Thus, investigations of this nature should not only lead to a greater understanding of the mechanisms governing the expression of MDR, but also provide a focus for pharmacologic intervention by a new class of inhibitors.
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MESH Headings
- 8-Bromo Cyclic Adenosine Monophosphate/analogs & derivatives
- 8-Bromo Cyclic Adenosine Monophosphate/pharmacology
- ATP Binding Cassette Transporter, Subfamily B, Member 1/biosynthesis
- ATP Binding Cassette Transporter, Subfamily B, Member 1/genetics
- ATP Binding Cassette Transporter, Subfamily B, Member 1/physiology
- Antineoplastic Agents/pharmacology
- Antineoplastic Agents/therapeutic use
- Breast Neoplasms/drug therapy
- Breast Neoplasms/genetics
- Breast Neoplasms/pathology
- Cyclic AMP-Dependent Protein Kinases/antagonists & inhibitors
- Cyclic AMP-Dependent Protein Kinases/physiology
- Drug Resistance, Multiple/genetics
- Gene Expression Regulation, Neoplastic
- Humans
- Neoplasm Proteins/biosynthesis
- Neoplasm Proteins/genetics
- Neoplasm Proteins/physiology
- Signal Transduction
- Transcription, Genetic
- Tumor Cells, Cultured
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Affiliation(s)
- R I Glazer
- Georgetown University Medical Center, Department of Pharmacology, Washington, DC 20007
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37
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Veron M, Radzio-Andzelm E, Tsigelny I, Ten Eyck LF, Taylor SS. A conserved helix motif complements the protein kinase core. Proc Natl Acad Sci U S A 1993; 90:10618-22. [PMID: 7504272 PMCID: PMC47828 DOI: 10.1073/pnas.90.22.10618] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Residues 40-300 of the mammalian catalytic (C) subunit of cAMP-dependent protein kinase define a conserved bilobal catalytic core shared by all eukaryotic protein kinases. Contiguous to the core is an extended amphipathic alpha-helix (A helix). Trp30, a prominent feature of this helix, fills a deep hydrophobic pocket between the two lobes on the surface opposite to the active site. The C subunit in Dictyostelium discoideum shows sequence conservation of residues 40-350 with the mouse enzyme but contains an N-terminal extension of 332 residues. A sequence corresponding to the A helix contiguous to the core is absent. However, we have now identified a remote A-helix motif (residues 77-98). When the core of the Dictyostelium C subunit was modeled, based on the mouse C subunit, complementarity between this putative A helix and the surface of the core was found to be conserved. Analysis of other protein kinases reveals that the A-helix motif is not restricted to cAMP-dependent protein kinase. In the Src-related family of protein kinases, for example, an A helix is very likely contiguous to the core, thus serving as a linker between the conserved catalytic core and the Src homology 2 domain. We predict that an A-helix motif complementary to the core will be a conserved feature of most eukaryotic protein kinases.
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Affiliation(s)
- M Veron
- Unité de Biochimie Cellulaire, Centre National de la Recherche Scientifique: URA1129, Institut Pasteur, France
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38
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A three-dimensional model of the Cdc2 protein kinase: localization of cyclin- and Suc1-binding regions and phosphorylation sites. Mol Cell Biol 1993. [PMID: 8336738 DOI: 10.1128/mcb.13.8.5122] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Cdc2 protein kinase requires cyclin binding for activity and also binds to a small protein, Suc1. Charged-to-alanine scanning mutagenesis of Cdc2 was used previously to localize cyclin A- and B- and Suc1-binding sites (B. Ducommun, P. Brambilla, and G. Draetta, Mol. Cell. Biol. 11:6177-6184, 1991). Those sites were mapped by building a Cdc2 model based on the crystallographic coordinates of the catalytic subunit of cyclic AMP-dependent protein kinase (cAPK) (D. R. Knighton, J. Zheng, L. F. Ten Eyck, V. A. Ashford, N.-H. Xuong, S. S. Taylor, and J. M. Sowadski, Science 253:407-414, 1991). On the basis of this model, additional mutations were made and tested for cyclin A and Suc1 binding and for kinase activity. Mutations that interfere with cyclin A binding are localized primarily on the small lobe near its interface with the cleft and include an acidic patch on the B helix and R-50 in the highly conserved PSTAIRE sequence. Two residues in the large lobe, R-151 and T-161, influence cyclin binding, and both are at the surface of the cleft near its interface with the PSTAIRE motif. Cyclin-dependent phosphorylation of T-161 in Cdc2 is essential for activation, and the model provides insights into the importance of this site. T-161 is equivalent to T-197, a stable phosphorylation site in cAPK. On the basis of the model, cyclin binding very likely alters the surface surrounding T-161 to allow for T-161 phosphorylation. The two major ligands to T-197 in cAPK are conserved as R-127 and R-151 in Cdc2. The equivalent of the third ligand, H-87, is T-47 in the PSTAIRE sequence motif. Once phosphorylated, T-161 is predicted to play a major structural role in Cdc2, comparable to that of T-197 in cAPK, by assembling the active conformation required for peptide recognition. The inhibitory phosphorylation at Y-15 also comes close to the cleft interface and on the basis of this model would disrupt the cleft interface and the adjacent peptide recognition site rather than prevent ATP binding. In contrast to cyclin A, both lobes influence Suc1 binding; however, the Suc1-binding sites are far from the active site. Several mutants map to the surface in cAPK, which is masked in part by the N-terminal 40 residues that lie outside the conserved catalytic core. The other Suc1-binding site maps to the large lobe near a 25-residue insert and includes R-215.
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Marcote MJ, Knighton DR, Basi G, Sowadski JM, Brambilla P, Draetta G, Taylor SS. A three-dimensional model of the Cdc2 protein kinase: localization of cyclin- and Suc1-binding regions and phosphorylation sites. Mol Cell Biol 1993; 13:5122-31. [PMID: 8336738 PMCID: PMC360168 DOI: 10.1128/mcb.13.8.5122-5131.1993] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The Cdc2 protein kinase requires cyclin binding for activity and also binds to a small protein, Suc1. Charged-to-alanine scanning mutagenesis of Cdc2 was used previously to localize cyclin A- and B- and Suc1-binding sites (B. Ducommun, P. Brambilla, and G. Draetta, Mol. Cell. Biol. 11:6177-6184, 1991). Those sites were mapped by building a Cdc2 model based on the crystallographic coordinates of the catalytic subunit of cyclic AMP-dependent protein kinase (cAPK) (D. R. Knighton, J. Zheng, L. F. Ten Eyck, V. A. Ashford, N.-H. Xuong, S. S. Taylor, and J. M. Sowadski, Science 253:407-414, 1991). On the basis of this model, additional mutations were made and tested for cyclin A and Suc1 binding and for kinase activity. Mutations that interfere with cyclin A binding are localized primarily on the small lobe near its interface with the cleft and include an acidic patch on the B helix and R-50 in the highly conserved PSTAIRE sequence. Two residues in the large lobe, R-151 and T-161, influence cyclin binding, and both are at the surface of the cleft near its interface with the PSTAIRE motif. Cyclin-dependent phosphorylation of T-161 in Cdc2 is essential for activation, and the model provides insights into the importance of this site. T-161 is equivalent to T-197, a stable phosphorylation site in cAPK. On the basis of the model, cyclin binding very likely alters the surface surrounding T-161 to allow for T-161 phosphorylation. The two major ligands to T-197 in cAPK are conserved as R-127 and R-151 in Cdc2. The equivalent of the third ligand, H-87, is T-47 in the PSTAIRE sequence motif. Once phosphorylated, T-161 is predicted to play a major structural role in Cdc2, comparable to that of T-197 in cAPK, by assembling the active conformation required for peptide recognition. The inhibitory phosphorylation at Y-15 also comes close to the cleft interface and on the basis of this model would disrupt the cleft interface and the adjacent peptide recognition site rather than prevent ATP binding. In contrast to cyclin A, both lobes influence Suc1 binding; however, the Suc1-binding sites are far from the active site. Several mutants map to the surface in cAPK, which is masked in part by the N-terminal 40 residues that lie outside the conserved catalytic core. The other Suc1-binding site maps to the large lobe near a 25-residue insert and includes R-215.
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Affiliation(s)
- M J Marcote
- Department of Chemistry, University of California, San Diego, La Jolla 92093-0654
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