Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.10.1 (ERK)
95,504 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The retinoid N-(hydroxyphenyl) retinamide (4-HPR) appears to be a promising tool for chemoprevention of breast carcinoma, and clinical trials to evaluate its effect are in progress. However, its action on tumor cells has remained largely undefined. We report here that 4-HPR induced apoptosis and/or differentiation in breast cancer cell lines, independent of hormone receptor status and retinoic acid receptor expression, although it was slightly more efficient in inhibiting proliferation of estrogen receptor-positive cells. 4-HPR up-modulated expression of several differentiation markers (class 1 HLA, laminin, and beta 1 integrin chain) and down-regulated expression of molecules associated with tumor progression, including the p185/HER2 oncoprotein, the epidermal growth factor receptor, and the M(r) 67,000 laminin receptor. These data suggest that 4-HPR could exert a beneficial effect by inhibiting cell proliferation and modulating breast tumor aggressiveness.
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PMID:Modulation of markers associated with tumor aggressiveness in human breast cancer cell lines by N-(4-hydroxyphenyl) retinamide. 754 8

G proteins serve as transducers between cell surface receptors and intracellular effectors. They consist of three subunits, termed alpha, beta, and gamma. Recently, it has been recognized that the beta gamma subunits play an active role such as activation of beta-adrenergic receptor kinase (beta ARK). The desensitization and down-regulation of beta-adrenergic receptors have been observed in the heart failure. beta ARK is one of the components involved in desensitization of beta-adrenergic receptor and it is reported, recently, that G protein beta gamma subunits bind beta ARK through the pleckstrin homology domain. Therefore, we investigated the effects of beta-adrenergic receptor stimulation on steady-state level of G protein beta subunits (G beta) in the rat heart. The whole rat heart was preliminarily perfused for 10 min by Langendorff's technique at 60 mmHg of hydrostatic pressure with Krebs-Henseleit bicarbonate buffer, and then perfused for 30 min in the same buffer with or without 10 microM isoproterenol (ISO), 0.1mM epinephrine (EPI), 10 microM ISO with 0.1mM propranolol (PROP), or 10 microM ISO with 10 microM CGP20712A (CGP). Immunoblotting using isoform-specific antisera against G protein beta subunits revealed that the rat heart contains at least three G protein beta subunits, beta 1, beta 2 and beta 3 at molecular weight of between 35,000 and 37,000. The level of G beta 3 in the cytosol dramatically decreased in the presence of ISO alone or ISO with CGP. G beta 3 decreased in the presence of EPI as well. Propranolol could block ISO-induced decrease of G beta 3 in the cytosol. In contrast, the levels of G beta 1 and G beta 2 didn't change in the presence of ISO or EPI. On the other hand, in membrane fractions the level of G beta 3 significantly increased in the presence of ISO or EPI. ISO with PROP or ISO with CGP did not change the level of G beta 3 in membrane fractions. The levels of G beta 1 and G beta 2 did not change in the presence of ISO or EPI in membrane fractions. Taken together, beta-adrenoceptor agonist might induce isoform-specific translocation of G beta 3 from the cytosol to the membrane.
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PMID:[Beta-adrenergic receptor-mediated changes in subcellular localization of G protein beta subunits in perfused rat hearts]. 759 Jun

Integrin receptors play important roles in organizing the actin-containing cytoskeleton and in signal transduction from the extracellular matrix. The initial steps in integrin function can be analyzed experimentally using beads coated with ligands or anti-integrin antibodies to trigger rapid focal transmembrane responses. A hierarchy of transmembrane actions was identified in this study. Simple integrin aggregation triggered localized transmembrane accumulation of 20 signal transduction molecules, including RhoA, Rac1, Ras, Raf, MEK, ERK, and JNK. In contrast, out of eight cytoskeletal molecules tested, only tensin coaccumulated. Integrin aggregation alone was also sufficient to induce rapid activation of the JNK pathway, with kinetics of activation different from those of ERK. The tyrosine kinase inhibitors herbimycin A or genistein blocked both the accumulation of 19 out of 20 signal transduction molecules and JNK- and ERK-mediated signaling. Cytochalasin D had identical effects, whereas three other tyrosine kinase inhibitors did not. The sole exception among signaling molecules was the kinase pp125FAK which continued to coaggregate with alpha 5 beta 1 integrins even in the presence of these inhibitors. Tyrosine kinase inhibition also failed to block the ability of ligand occupancy plus integrin aggregation to trigger transmembrane accumulation of the three cytoskeletal molecules talin, alpha-actinin, and vinculin; these molecules accumulated even in the presence of cytochalasin D. However, it was necessary to fulfill all four conditions, i.e., integrin aggregation, integrin occupancy, tyrosine kinase activity, and actin cytoskeletal integrity, to achieve integrin-mediated focal accumulation of other cytoskeletal molecules including F-actin and paxillin. Integrins therefore mediate a transmembrane hierarchy of molecular responses.
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PMID:Integrin function: molecular hierarchies of cytoskeletal and signaling molecules. 759 97

It is well-established that agonist-mediated desensitization of the beta 2-adrenergic receptor (beta 2AR) involves its phosphorylation by protein kinase A (PKA) and the beta AR kinase (beta ARK). The phosphorylated receptor is less efficient at mediating agonist stimulation of adenylyl cyclase activity. The result is an increase in the concentration of agonist required for half-maximal stimulation (EC50) and a reduction in maximal stimulation (Vmax). As less is known about desentization of the human beta 1 AR, we compared the desensitization pattern of human beta 1 AR and beta 2AR stably expressed in two different hamster cell lines: Chinese hamster ovary (CHO), and Chinese hamster fibroblast (CHW). Following agonist treatment, all of the cell lines exhibited an increase in EC50, and a reduction in Vmax was observed in CHO-beta 2 but not beta 1 cells. CHW-beta 1 cells were resistant to acute agonist-mediated reduction in Vmax compared to CHW-beta 2 cells. More prolonged agonist exposure produced a modest reduction in Vmax and this effect was more noticeable when the CHW cells expressed lower levels of beta 1AR. To explore the role of protein kinases in these effects, digitonin-permeabilized CHW cells were loaded either with heparin (a beta ARK inhibitor) or a peptide inhibitor of PKA and exposed to agonist. In both beta 2AR- and beta 1AR-expressing cells, heparin inhibited the reduction in Vmax and the PKA inhibitor blocked the increase in EC50. Finally, exposing CHW cells expressing either subtype to a permeable cyclic AMP derivative caused an increase in EC50 similar to that observed in agonist-treated cells, but without any reduction in maximal activity. Our data suggest that whereas PKA-mediated desensitization is not subtype-specific, human beta 1AR is more resistant to beta ARK-mediated desensitization compared to the human beta 2AR.
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PMID:Differences in desensitization between human beta 1- and beta 2-adrenergic receptors stably expressed in transfected hamster cells. 766 9

A motor neuron disorder resembling that of amyotrophic lateral sclerosis was found in a patient who had received the intramuscular administration of a mixture of bovine brain gangliosides (Yuki, N., Sato, S., Miyatake, T., Sugiyama, K., Katagiri, T., and Sasaki, H. (1991) Lancet 337, 1109-1110). A very high titer of anti-GM2 IgM was detected in the patient's serum and the patient quickly recovered after plasmapheresis. The clinical course of the patient appeared to be different from amyotrophic lateral sclerosis and the anti-GM2 IgM was thought to be the culprit. The IgM reacted with GM2, GM1b-GalNAc, SPG(alpha 2-3)-GalNAc, and GD1a-GalNAc, but not with GA2 or GD2, meaning that the epitope recognized by the IgM was the GM2-like terminal structure, GalNAc beta 1-4(Neu-Ac alpha 2-3)Gal beta 1-. In this study, we found two novel GM2-epitope containing gangliosides, X1 and X2, in bovine brain gangliosides by TLC immunostaining using the patient's IgM. They were characterized as unique lacto-ganglio type gangliosides containing the following branching structures. [formula: see text] Their unusual structures may be immunogenic to humans to induce anti-GM2 antibody.
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PMID:Novel lacto-ganglio type gangliosides with GM2-epitope in bovine brain which react with IgM from a patient of the amyotrophic lateral sclerosis-like disorder. 769 4

Alkaline borohydride-reduced keratan sulphate chains from bovine articular cartilage (6-8-year-old animals) were subjected to a limit digest with the enzyme keratanase II. Using 1H-NMR spectroscopy, 25 reduced oligosaccharides deriving from keratan sulphate were shown to have the following structures [GlcNAc(6S)-ol represents N-acetylglucosaminitol 6-O-sulphate]: Gal beta 1-4-GlcNAc(6S)-ol, Gal beta 1-4GlcNAc(6S)beta 1-3Gal beta 1-4GlcNAc(6S)-ol, Gal(6S)beta 1-4GlcNAc(6S)-ol, Gal-(6S)beta 1-4GlcNAc(6S) beta 1-3Gal beta 1-4GlcNAc(6S)-ol, Gal beta 1-4GlcNAc(6S)beta 1-3Gal(6S)beta 1-4GlcNAc(6S)-ol, Gal(6S)beta 1-4GlcNAc(6S)beta 1-3Gal(6S)1-4GlcNAc(6S)-ol, Gal beta 1-4(Fuc alpha 1-3)GlcNAc(6S)-ol, Gal beta 1-4-(Fuc alpha 1-3)GlcNAc(6S)beta1-3Gal beta 1-4(Fuc alpha 1-3)GlcNAc(6S)-ol, Gal beta 1-4GlcNAc(6S)beta 1-3Gal beta 1-4(Fuc alpha 1-3)-GlcNAc(6S)-ol, Gal beta 1-4(Fuc alpha 1-3)GlcNAc(6S)beta 1-3Gal beta 1-4GlcNAc(6S)-ol, Gal(6S) beta 1-4GlcNAc-(6S)beta 1-3Gal beta 1-4(Fuc alpha 1-3)GlcNAc(6S)-ol, Gal beta 1-4(Fuc alpha 1-3)GlcNAc(6S)beta 1-3Gal(6S)1-4GlcNAc(6S)-ol, Gal beta 1-4GlcNAc(6S)beta 1-6(Gal beta 1-3)GalNAc-ol, Gal beta 1-4GlcNAc(6S) beta1-6(NeuAc2-3Gal beta 1-3)Gal-NAc-ol, Gal beta 1-4GlcNAc(6S)beta 1-3Gal beta 1-4GlcNAc(6S)beta 1-6(Gal beta 1-3) GalNAc-ol, Gal(6S)beta 1-4GlcNAc-(6S)beta 1-6(Gal beta 1-3)GalNAc-ol, Gal beta 1-4GlcNAc(6S)beta 1-3Gal beta 1-4GlcNAc(6S)beta 1-6(NeuAc2-3Gal beta 1-3)-GalNAc-ol, Gal(6S)beta 1-4GlcNAc(6S)beta 1-6(NeuAc alpha 2-3Gal beta 1-3)GalNAc-ol, Gal(6S) beta 1-4GlcNAc-(6S)beta 1-3Gal beta 1-4GlcNAc(6S)beta 1-6(Gal beta 1-3)GalNAc- ol, Gal(6S)beta 1-4GlcNAc(6S)beta 1-3Gal beta 1-4GlcNAc-(6S)beta 1-6(NeuAc alpha 2-3Gal beta 1-3)GalNAc-ol, NeuAc alpha 2-6Gal beta 1-4GlcNAc(6S)beta 1-3Gal beta 1-4GlcNAc(6S)-ol, NeuAc alpha 2-3Gal beta 1-4GlcNAc(6S)beta 1-3Gal beta 1-4GlcNAc(6S)-ol, NeuAc alpha 2-6Gal beta 1-4GlcNAc(6S)beta 1-3Gal-(6S)beta 1-4GlcNAc(6S)-ol, NeuAc alpha 2-3Gal beta 1-4GlcNAc(6S)beta 1-3Gal(6S)beta 1-4GlcNAc(6S)-ol and Neu-Ac alpha 2-3Gal(6S)beta 1-4GlcNAc(6S)beta 1-3Gal(6S beta)1-4GlcNAc(6S)-ol. Proton chemical shifts for these oligosaccharides were assigned using one- and two-dimensional NMR spectroscopic methods. These results confirm the findings of Nakazawa et al. [Nakazawa, K., Ito, M., Yamagata, T. and Suzuki, S. (1989) in Keratan sulphate: chemistry, biology and chemical pathology (Greiling, H. and Scott, J.E., eds) pp. 99-110, The Biochemical Society, London], namely that keratanase II cleaves the O-glycosidic bond of a beta(1-3)-linked 6-O-sulphated N-acetylglucosamine.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Oligosaccharides derived by keratanase II digestion of bovine articular cartilage keratan sulphates. 792 42

HER2/neu-overexpressing tumor cell lines are relatively resistant to lymphokine-activated killer (LAK) cell cytotoxicity when compared to HER2/neu-nonexpressing lines. HER2/neu+ targets were also resistant to binding by LAK large granular lymphocytes (LGL) as shown by visualization at the single-cell level, a target monolayer binding assay and in "cold" target inhibition experiments. HER2/neu+ LAK-resistant ovarian cell lines demonstrated an absence of ICAM-1 expression while expression of LFA-3, N-CAM, laminin and beta 1 integrins was comparable to that of HER2/neu- targets. In contrast, the HER2/neu+ breast cell line, SKBR-3, which was also resistant to lysis and binding by LAK LGL, demonstrated normal expression of ICAM-1. Anti-ICAM-1 antibodies blocked binding and lysis of HER2/neu- carcinoma targets by LAK cells, further supporting the notion that lack of ICAM-1 expression on HER2/neu+ cells contributes to their resistance. The modest binding and lysis of HER2/neu+ targets by LAK cells was significantly inhibited by anti-LFA-1 antibodies, suggesting the existence of another counter-receptor for LFA-1 on HER2/neu+ targets. The following also supported deficiencies in post-binding events when HER2/neu+ cells resisted the lytic activity of LAK cells: (a) when the relative resistance to effector cell binding was overcome by exogenous lectin. HER2/neu+ cell lines were still resistant to LAK cytolysis, and (b) HER2/neu+ targets were resistant to perforin-containing granule extracts obtained from the CTLL-R8 cytotoxic lymphocyte cell line. These results indicate that deficiency in effector binding as well as post-binding events contributes to the resistance of HER2/neu-overexpressing tumor targets to LAK-cell-mediated lysis.
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PMID:Resistance of HER2/neu-overexpressing tumor targets to lymphokine-activated-killer-cell-mediated lysis: evidence for deficiency of binding and post-binding events. 809 27

Two gangliosides were efficiently synthesized from asialo-GM1 (Gal beta 1-3GalNAc beta 1-4Gal beta 1-4Glc beta 1-1 Cer) and cytidine 5'-phosphate-N-acetylneuraminic acid (CMP-NeuAc) by using sialyltransferases in rat liver Golgi vesicles in vitro. These gangliosides were rapidly purified by a combination of anion exchange and reverse-phase column chromatographies. The ganglioside structures were determined by TLC analysis, treatment with a sialidase from Salmonella typhimurium LT2, which specifically hydrolyzes alpha 2-3 N-acetylneuraminic acid (NeuAc alpha 2-3) linkages, TLC immunostaining, and 1H-NMR spectroscopy. One of the gangliosides was identified as GD1 alpha [Neu-Ac alpha 2-3Gal beta 1-3(NeuAc alpha 2-6)GalNAc beta 1-4Gal beta 1-4Glc beta 1-1 Cer]. The other ganglioside was determined to be GM1b (NeuAc alpha 2-3Gal beta 1-3GalNAc beta 1-4Gal beta 1-4Glc beta 1-1 Cer), which has been reported in a previous study [Pohlentz, G., Klein, D., Schmitz, D., Schwarzmann, G., Peter-Katalinic, J. & Sandhoff, K. (1988) Biol. Chem. Hoppe-Seyler 369, 55-63]. Finally, GM1b and GD1 alpha were obtained from asialo-GM1 as a starting material in 8.1% and 1.2% overall yields, respectively. This study also suggests that the novel synthetic pathway asialo-GM1-->GM1b-->GD1 alpha may exist in rat liver.
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PMID:In vitro synthesis of disialoganglioside (GD1 alpha) from asialo-GM1 using sialyltransferases in rat liver Golgi vesicles. 816 48

Gal beta 1-->3GalN beta 1-->4Gal(3<--2 alpha Neu)beta 1-->4Glc beta-->1Sph (WILD20), a new glycosphingolipid, a breakdown product of the monosialoganglioside GM1 obtained through alkaline hydrolysis, shows dose-dependent platelet anti-aggregating properties in vitro and in vivo. This effect is agonist- and species-independent. The family of lysosphingolipids, to which the compound belongs, is present in platelets particularly after thrombin treatment. WILD20 antiplatelet effect is due to the interference with ADP or thrombin-induced aggregation, probably via phospholipase A2 (PLA2) blockade; the substance is also effective when arachidonic acid is used as an agonist. Serotonin blood levels are also reduced. The substance, orally active at dosages of 0.1-0.01 mg/kg as antiplatelets agent, prolonged bleeding time without interfering with the coagulative or fibrinolytic processes.
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PMID:Antiplatelet effects of a new de-N-acetyl-lyso-glycosphingolipid. 822 63

The beta and gamma subunits of heterotrimeric guanine nucleotide-binding proteins (G proteins) have recently been shown to play an active role in signal transduction. Among other effects they enable translocation of the beta-adrenergic receptor kinase (beta ARK) from the cytosol to the plasma membrane and thus permit phosphorylation and ultimately desensitization of beta-adrenergic receptors and other G-protein-coupled receptors. To investigate the specificity of this effect, we have purified various combinations of recombinant beta and gamma subunits expressed in Sf9 cells and measured their effects on beta ARK-catalyzed phosphorylation of beta 2-adrenergic receptors and of rhodopsin. The combinations tested were beta 1 gamma 2, beta 1 gamma 3, beta 2 gamma 2, beta 2 gamma 3, and transducin beta gamma (beta 1 gamma 1). There were clear differences in enhancement of rhodopsin phosphorylation, with an order of efficacy beta 2 gamma 2 > beta 1 gamma 2 >> beta 2 gamma 3 approximately beta 1 gamma 3 approximately beta 1 gamma 1. The first two combinations had larger effects than a mixed beta gamma preparation from bovine brain. In enhancing phosphorylation of beta 2-adrenergic receptors, beta 1 gamma 2 was more efficient and potent than all other combinations. These data suggest a twofold specificity of beta gamma complexes in enhancing beta ARK-catalyzed receptor phosphorylation: the gamma subunits may be important in interacting with beta ARK, with gamma 2 being more potent than gamma 3, whereas the beta subunits may determine coupling to the receptors, with beta 2 being more effective than beta 1 for rhodopsin and beta 1 being more effective than beta 2 for beta 2-adrenergic receptors.
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PMID:Specific enhancement of beta-adrenergic receptor kinase activity by defined G-protein beta and gamma subunits. 824 28


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