Ferenc Erdődi
University of Debrecen, Department of Medical Chemistry, Faculty Member
Transient transfection of NIH3T3 cells with various constructs of myosin phosphatase target subunit (MYPT1) and GFP showed distinct cellular localizations. Constructs containing the N-terminal nuclear localization signals (NLS), i.e.... more
Transient transfection of NIH3T3 cells with various constructs of myosin phosphatase target subunit (MYPT1) and GFP showed distinct cellular localizations. Constructs containing the N-terminal nuclear localization signals (NLS), i.e. full-length MYPT1 and N-terminal MYPT1 fragments, were concentrated in the nucleus. Full-length chicken and human MYPT1-GFP showed discrete nuclear foci. Deletion of the N-terminal NLS or use of central or C-terminal MYPT1 fragments did not show unique nuclear distributions (C-terminal NLS are present). Transient transfection of NIH3T3 cells (in the presence of serum) with full-length MYPT1-GFP caused a marked decrease in number of attached cells, an apparent block in the cell cycle prior to M phase and signs of increased apoptosis. Under conditions of serum starvation the unique nuclear localization of MYPT1-GFP was not found and there was no marked decrease in the number of attached cells (after 48 h). Stable transfection of HEK 293 cells with GFP-MYPT1 was obtained. MYPT1 and its N-terminal mutants bound to retinoblastoma protein (Rb), raising the possibility that Rb is implicated in the effects caused by overexpression of MYPT1.
Research Interests: Physiology, Biology, Cell Cycle, Cell Biology, Medicine, and 15 moreCell line, Humans, Mutation, Phosphatase, Mice, Animals, Medical Physiology, Retinoblastoma, Cell nucleus, Rats, Recombinant Proteins, Neurosciences, Nuclear localization signal, Biochemistry and cell biology, and Nuclear Localization
Research Interests: Chemistry, Medicine, Biological Sciences, Smooth muscle, Mutation, and 15 morePhosphatase, cyclic AMP, Animals, Myosin, Phosphorylation, Biochemical, High Pressure Liquid Chromatography, Kinase, CHEMICAL SCIENCES, Chickens, Amino Acid Sequence, Protein Binding, Protein Transport, Molecular Sequence Data, and Medical and Health Sciences
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... Foreword xxiii Preface xxv xxi CONTRACTILE PROTEINS CHAPTER 1 Myosin Structure and Function ROBERT S. ADELSTEIN AND JAMES ... SIGNAL TRANSDUCTION CHAPTER 20 The Nitric Oxide-Cyclic GMP Signaling System THOMAS M. LINCOLN, TRUDY L.... more
... Foreword xxiii Preface xxv xxi CONTRACTILE PROTEINS CHAPTER 1 Myosin Structure and Function ROBERT S. ADELSTEIN AND JAMES ... SIGNAL TRANSDUCTION CHAPTER 20 The Nitric Oxide-Cyclic GMP Signaling System THOMAS M. LINCOLN, TRUDY L. CORNWELL ...
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ABSTRACT Protein phosphatases assayed with phosphorylase alpha are present in the soluble and particulate fractions of rat thymocytes. Phosphorylase phosphatase activity in the cytosol fraction was resolved by heparin-Sepharose... more
ABSTRACT Protein phosphatases assayed with phosphorylase alpha are present in the soluble and particulate fractions of rat thymocytes. Phosphorylase phosphatase activity in the cytosol fraction was resolved by heparin-Sepharose chromatography into type-1 and type-2A enzymes. Similarities between thymocyte and muscle or liver protein phosphatase-1 included preferential dephosphorylation of the beta subunit of phosphorylase kinase, inhibition by inhibitor-2 and retention by heparin-Sepharose. Similarities between thymocyte and muscle or liver protein phosphatase-2A included specificity for the alpha subunit of phosphorylase kinase, insensitivity to the action of inhibitor-2, lack of retention by heparin-Sepharose and stimulation by polycationic macromolecules such as polybrene, protamine and histone H1. Protein phosphatase-1 from the cytosol fraction of thymocytes had an apparent molecular mass of 120 kDa as determined by gel filtration. The phosphatase-2A separated from the cytosol of thymocytes may correspond to phosphatase-2A0, since it was completely inactive (latent) in the absence of polycation and had activity only in the presence of polycations. The apparent molecular mass of phosphatase-2A0 from thymocytes was 240 kDa as determined by gel filtration. The catalytic subunit of thymocyte type-1 protein phosphatase was purified with heparin-Sepharose chromatography followed by gel filtration and fast protein liquid chromatography on Mono Q column. The purified type-1 catalytic subunit exhibited a specific activity of 8.2 U/mg and consisted of a single protein of 35 kDa as judged by SDS-gel electrophoresis. The catalytic subunit of type-2A phosphatase from thymocytes appearing in the heparin-Sepharose flow-through fraction was further purified on protamine-Sepharose, followed by gel filtration. The specific activity of the type-2A catalytic subunit was 2.1 U/mg and consisted of a major protein of 34.5 kDa, as revealed by SDS-gel electrophoresis.
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The objective of this study was to relate the toxicity of several cantharidin-derivative pesticides with their abilities to inhibit protein phosphatases-1 (PP1) and -2A (PP2A). Cantharidin (CA), endothall, and endothall thioanhydride... more
The objective of this study was to relate the toxicity of several cantharidin-derivative pesticides with their abilities to inhibit protein phosphatases-1 (PP1) and -2A (PP2A). Cantharidin (CA), endothall, and endothall thioanhydride (ETA) inhibited the activity of PP1 and PP2A, and the potency sequence was CA > endothall > ETA in vitro. We determined the inhibitory potency of these pesticides on hepatic protein phosphatases by administration of the toxins into the portal vein of rats. The potency sequence of ETA > CA > endothall was established for the inhibition of PP1 and PP2A in vivo and shows close correlation with the sequence of relative toxicity. ETA predominantly targets PP1 for inhibition in liver, as revealed by assays specific for PP1 or PP2A. Studies using 3T3 fibroblasts showed that only ETA, but not CA or endothall, induced marked morphological changes. These effects included cell rounding and detachment as well as extensive reorganization of actin filamen...
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Research Interests: Chemistry, Organic Chemistry, Medicine, Humans, Phosphatase, and 14 moreSelenium, Stereochemistry, Surface plasmon resonance, Peptides, Protein Phosphatase 2A, HeLa cells, Acetylation, Bioorganic and medicinal Chemistry, Protein Binding, Cell Survival, Aryl, Glycosides, binding sites, and Pharmacology and pharmaceutical sciences
The Gram-negative bacterium Pseudomonas aeruginosa is an important opportunistic human pathogen associated with cystic fibrosis. P. aeruginosa produces two soluble lectins, the d-galactose-specific lectin PA-IL (LecA) and the... more
The Gram-negative bacterium Pseudomonas aeruginosa is an important opportunistic human pathogen associated with cystic fibrosis. P. aeruginosa produces two soluble lectins, the d-galactose-specific lectin PA-IL (LecA) and the l-fucose-specific lectin PA-IIL (LecB), among other virulence factors. These lectins play an important role in the adhesion to host cells and biofilm formation. Moreover, PA-IL is cytotoxic to respiratory cells in the primary culture. Therefore, these lectins are promising therapeutic targets. Specifically, carbohydrate-based compounds could inhibit their activity. In the present work, a 3-O-fucosyl lactose-containing tetravalent glycocluster was synthesized and utilized as a mutual ligand of galactophilic and fucophilic lectins. Pentaerythritol equipped with azido ethylene glycol-linkers was chosen as a multivalent scaffold and the glycocluster was constructed by coupling the scaffold with propargyl 3-O-fucosyl lactoside using an azide-alkyne 1,3-dipolar cyclo...
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Protein phosphatase Z (Ppz) is a fungus specific enzyme that regulates cell wall integrity, cation homeostasis and oxidative stress response. Work on Saccharomyces cerevisiae has shown that the enzyme is inhibited by Hal3/Vhs3... more
Protein phosphatase Z (Ppz) is a fungus specific enzyme that regulates cell wall integrity, cation homeostasis and oxidative stress response. Work on Saccharomyces cerevisiae has shown that the enzyme is inhibited by Hal3/Vhs3 moonlighting proteins that together with Cab3 constitute the essential phosphopantothenoylcysteine decarboxylase (PPCDC) enzyme. In Candida albicans CaPpz1 is also involved in the morphological changes and infectiveness of this opportunistic human pathogen. To reveal the CaPpz1 regulatory context we searched the C. albicans database and identified two genes that, based on the structure of their S. cerevisiae counterparts, were termed CaHal3 and CaCab3. By pull down analysis and phosphatase assays we demonstrated that both of the bacterially expressed recombinant proteins were able to bind and inhibit CaPpz1 as well as its C-terminal catalytic domain (CaPpz1-Cter) with comparable efficiency. The binding and inhibition were always more pronounced with CaPpz1-Cte...
Research Interests: Biochemistry, Biology, Medicine, Multidisciplinary, Saccharomyces cerevisiae, and 12 morePhylogeny, Enzyme regulation, Phosphatase, Polymerase Chain Reaction, Candida albicans, Yeast, PLoS one, Protein Phosphatase 2A, Protein Expression, Recombinant Proteins, Opportunistic Infections, and Protein subunits
Type 1 (PP1) and type 2A (PP2A) phosphatase activity was measured in three subcellular fractions of human platelets. About 80% of the activity was in the high-speed supernatant. Western blots showed that the catalytic subunit of PP1... more
Type 1 (PP1) and type 2A (PP2A) phosphatase activity was measured in three subcellular fractions of human platelets. About 80% of the activity was in the high-speed supernatant. Western blots showed that the catalytic subunit of PP1 (PP1c), including α- and δ-isoforms, was present in each fraction, but the level of the catalytic subunit of PP2A was very low in the low-speed pellet (cytoskeletal fraction). Various antibodies detected a subunit similar to the 130 kDa subunit (M130) of myosin phosphatase (MP) of smooth muscle in the low- and the high-speed pellets of human platelets. PP1c and associated proteins were isolated by microcystin-Sepharose. Many proteins were separated from each fraction, including myosin, actin and PP1c. M130 was separated only from the low-speed and the high-speed pellets. Kinase activities were detected in the unbound fractions, and fractions from the low- and high-speed pellets phosphorylated M130 and myosin respectively. Treatment of platelets with caly...
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The effect of immobilization by plaster cast was studied on the activities of phosphoglucomutase (PGM), pyruvate kinase ( PyK ) and cAMP-dependent protein kinase in fast (extensor digitorum longus [EDL]), and slow (soleus) muscles of... more
The effect of immobilization by plaster cast was studied on the activities of phosphoglucomutase (PGM), pyruvate kinase ( PyK ) and cAMP-dependent protein kinase in fast (extensor digitorum longus [EDL]), and slow (soleus) muscles of rats. In control untreated animals, PGM and PyK activities are 3 and 5 fold higher respectively in EDL than in soleus in correlation with the high glycolytic activity of fast muscles. During the four weeks period of immobilization a 20% decrease occurred in PGM activity, to which no limiting role in glycolysis is attributed, while PyK which has a regulatory function, showed a 35% decrease in EDL; at the same time in the soleus the activity of these enzymes did not change. The decrease of PGM and PyK activity in EDL diminished the difference between the slow and fast muscles, and it was evaluated as a tendency to dedifferentiation (transformation). The activity of cAMP-dependent protein kinase, in contrast to the glycolytic enzymes, was higher in the sol...
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Research Interests: Physiology, Skeletal muscle biology, Biology, Calcium, Myogenesis, and 15 moreEnzyme Inhibitors, Medicine, Cell Differentiation, Phosphatase, Animals, Myosin, Phosphorylation, Protein Phosphatase 2A, Enzyme, Skeletal Muscle, Myocyte, Light chain, Biochemistry and cell biology, Okadaic acid, and Muscle fibers skeletal
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The dissociated regulatory subunit (RII) of autophosphorylated cAMP‐dependent protein kinase II was dephosphorylated by the catalytic subunits of protein phosphatase‐1 and ‐2A (phosphatase‐1c and ‐2Ac) and by a high‐M r,... more
The dissociated regulatory subunit (RII) of autophosphorylated cAMP‐dependent protein kinase II was dephosphorylated by the catalytic subunits of protein phosphatase‐1 and ‐2A (phosphatase‐1c and ‐2Ac) and by a high‐M r, polycation‐dependent form of phosphatase‐2A (2A0) with K m values of 5,0.3 and 1 μM, respectively. Dissociation of protein kinase by cAMP preferentially increased the dephosphorylation of RII by phosphatase‐1c, whereas polycations (histone H1 or polybrene) markedly stimulated phosphatase‐2Ac and ‐2Ao even in the absence of cAMP. Thiophosphorylated RII inhibited the dephosphorylation of phosphorylase a by these phosphatases with half‐maximum inhibitory concentrations of 0.1–0.36 μM.
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Research Interests: Biochemistry, Physiology, Chromatography, Biology, Enzyme Inhibitors, and 15 moreMedicine, Neurospora crassa, Humans, Phosphatase, Animals, Ethanol, Enzyme, Microcystins, Chemical Precipitation, Molecular weight, Ammonium Sulfate, Cantharidin, Biochemistry and cell biology, Okadaic acid, and Dicarboxylic Acids
Research Interests: Chemistry, Kinetics, Fluorescence Microscopy, Membrane Proteins, Medicine, and 15 moreCell line, Humans, Endothelial Cells, Phosphatase, Animals, Surface plasmon resonance, Phosphorylation, Biochimie, Endothelial cell, Protein Binding, Light chain, Biochemistry and cell biology, Dephosphorylation, Cell Membrane, and Glycogen Synthase Kinase
The myosin phosphatase (MP) composed of the catalytic subunit of type 1 protein phosphatase and myosin phosphatase target subunit isoform 1 (MYPT1) was identified as the major serine/threonine phosphatase component in the... more
The myosin phosphatase (MP) composed of the catalytic subunit of type 1 protein phosphatase and myosin phosphatase target subunit isoform 1 (MYPT1) was identified as the major serine/threonine phosphatase component in the platelet-cytoskeleton fraction. MYPT1 was phosphorylated by cytoskeletal kinase(s), but the identity of the kinase(s) and the effect of phosphorylation were not established. Incubation of platelet-cytoskeletal fraction with MgATP or MgATP[S] (magnesium adenosine 5′-[γ-thio]triphosphate) caused a decrease in the 20kDa light-chain of smooth-muscle myosin (MLC20) phosphatase and phosphorylase phosphatase activities. MYPT1 contains a phosphorylation site, Thr-695, involved in the inhibition of MP in a RhoA/Rho kinase-dependent manner. The cytoskeletal kinase(s) phosphorylated Thr-695 of glutathione S-transferase (GST)-MYPT1, as determined with an antibody specific for phosphorylated Thr-695. The level of Rho kinase was low in the cytoskeletal fraction and was detected ...
Research Interests: Chemistry, Biology, Medicine, Cytoskeleton, Biological Sciences, and 13 moreHumans, Phosphorylation, Biochemical, Mitogen Activated Protein Kinase, CHEMICAL SCIENCES, Adult, K Map, Adenosine Triphosphate, binding sites, Blood platelets, Medical and Health Sciences, In Vitro Techniques, and Protein subunits
The catalytic subunits of protein phosphatase-1 and 2A were covalently modified in their reactive sulfhydryl groups with N-(3-Pyrene) maleimide resulting in fluorescent labeling of the proteins to an extent of 0.85 and 0.9 mole dye/mole... more
The catalytic subunits of protein phosphatase-1 and 2A were covalently modified in their reactive sulfhydryl groups with N-(3-Pyrene) maleimide resulting in fluorescent labeling of the proteins to an extent of 0.85 and 0.9 mole dye/mole enzyme, respectively. The reaction of the sulfhydryl group led to the partial inactivation of both phosphatase-1 and 2A. Inhibitor-1 and inhibitor-2 increased markedly the fluorescence intensity of the dye-phosphatase-1 conjugate implying that the labeled enzyme retained its ability to bind these proteins. In contrast, inhibitor-1 or inhibitor-2 had no influence on the fluorescence of the dye-phosphatase-2A conjugate. No change in either the fluorescence intensity or polarization of labeled phosphatase-1 and 2A was observed in the presence of thiophosphorylase a, suggesting a lack of interaction of these enzyme forms with the substrate after modification of the reactive sulfhydryl group.
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A mechanism proposed for regulation of myosin phosphatase (MP) activity is phosphorylation of the myosin phosphatase target subunit (MYPT1). Integrin-linked kinase (ILK) is associated with the contractile machinery and can phosphorylate... more
A mechanism proposed for regulation of myosin phosphatase (MP) activity is phosphorylation of the myosin phosphatase target subunit (MYPT1). Integrin-linked kinase (ILK) is associated with the contractile machinery and can phosphorylate myosin at the myosin light-chain kinase sites. The possibility that ILK may also phosphorylate and regulate MP was investigated. ILK was associated with the MP holoenzyme, shown by Western blots and in-gel kinase assays. MYPT1 was phosphorylated by ILK and phosphorylation sites in the N- and C-terminal fragments of MYPT1 were detected. From sequence analyses, three sites were identified: a primary site at Thr709, and two other sites at Thr695 and Thr495. One of the sites for cAMP-dependent protein kinase (PKA) was Ser694. Assays with the catalytic subunit of type 1 phosphatase indicated that only the C-terminal fragment of MYPT1 phosphorylated by zipper-interacting protein kinase, and ILK inhibited activity. The phosphorylated N-terminal fragment act...
Research Interests: Chemistry, Medicine, Biological Sciences, Smooth muscle, Mutation, and 15 morePhosphatase, cyclic AMP, Animals, Myosin, Phosphorylation, Biochemical, High Pressure Liquid Chromatography, Kinase, CHEMICAL SCIENCES, Chickens, Amino Acid Sequence, Protein Binding, Protein Transport, Molecular Sequence Data, and Medical and Health Sciences
Identification of the interacting proteins of protein phosphatases is crucial to understand the cellular roles of these enzymes. Microcystin-LR (MC-LR), a potent inhibitor of protein phosphatase-1 (PP1), -2A (PP2A), PP4, PP5 and PP6, was... more
Identification of the interacting proteins of protein phosphatases is crucial to understand the cellular roles of these enzymes. Microcystin-LR (MC-LR), a potent inhibitor of protein phosphatase-1 (PP1), -2A (PP2A), PP4, PP5 and PP6, was biotinylated, immobilized to streptavidin-coupled sensorchip surface and used in surface plasmon resonance (SPR) based binding experiments to isolate phosphatase binding proteins. Biotin-MC-LR captured PP1 catalytic subunit (PP1c) stably and the biotin-MC-LR-PP1c complex was able to further interact with the regulatory subunit (MYPT1) of myosin phosphatase. Increased biotin-MC-LR coated sensorchip surface in the Surface Prep unit of Biacore 3000 captured PP1c, PP2Ac and their regulatory proteins including MYPT1, MYPT family TIMAP, inhibitor-2 as well as PP2A-A and -Bα-subunits from normal and UVA-irradiated HaCaT cell lysates as revealed by dot blot analysis of the recovered proteins. Biotin-MC-LR was used for the subcellular localization of protein...
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Research Interests: Fluorescence Microscopy, Biology, Medicine, Gene Silencing, Biological Sciences, and 13 moreCell line, Humans, Mice, Animals, Male, Physical sciences, Skin, Protein Phosphatase 2A, Clinical Sciences, Homeostasis, Biochemistry and cell biology, Ultraviolet Rays, and Medical biochemistry and metabolomics
The role of nitric oxide (NO) in the pathophysiology of inflammatory bowel disease (IBD) is controversial. The aim of this study was to investigate the expression and localization of nitric oxide synthase isoforms (iNOS, eNOS) in IBD... more
The role of nitric oxide (NO) in the pathophysiology of inflammatory bowel disease (IBD) is controversial. The aim of this study was to investigate the expression and localization of nitric oxide synthase isoforms (iNOS, eNOS) in IBD colonic mucosa. Forty-four patients with IBD (24 ulcerative colitis (UC), 20 Crohn's disease (CD) and 16 controls) were investigated by colonoscopy. iNOS and eNOS in tissue sections was demonstrated by histochemistry (NADPH-diaphorase reaction) and immunohistochemistry. Cell type analysis and quantitative assessment of the iNOS immunoreactive (IR) cells and densitometry of iNOS in immunoblots were also performed. iNOS-IR cells were significantly numerous in inflamed mucosa of UC (64+/-4 cells/mm2) than in CD (4+/-2 cells/mm2). iNOS-IR/CD15-IR cells showed significant elevation in inflamed (i) versus uninflamed (u) UC mucosa (UCu 8+/-3%, UCi 85+/-10%) In CD, the percentage of iNOS-IR/CD68-IR cells was lower in inflamed sites (CDu 23+/-8%, CDi 4+/-3%). Immunoblot of biopsies revealed significant elevation of iNOS in active UC compared with uninflamed sites, whereas in CD no significant changes were detected. Differences were observed in eNOS and endothelial marker CD31 immunoreactivity. In patients with UC and in controls the ratios of eNOS/CD31-IR vessels were 82.3% and 92.0% respectively, whereas in CD the ratio was 8.3% with a concomitantly significant increase of CD31-IR vessels. The distribution and morphological characteristics of the NOS-IR inflammatory cells and endothelia were similar to those showing NADPH-diaphorase reactivity. Differences observed in the expression and distribution of NOS isoforms in immune and endothelial cells may contribute to better understanding of the structural and physiological changes in UC and CD.