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  • 1
    ISSN: 0730-2312
    Schlagwort(e): redox ; HgCl2 ; tyrosine phosphorylation ; p56lck ; signal complex ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: Previously we showed that a thiol-reactive heavy metal, HgCl2, crosslinked multiple cell surface receptors through a ligand-independent pathway, which produced massive aggregates of phosphotyrosine (PTYR)-containing proteins beneath plasma membrane [Nakashima et al. (1994): J Immunol 152:1064-1071]. In this study we characterized these unique aggregates at the molecular level. The lysates in Brij 96 of thymocytes treated with HgCl2 were separated into the supernatant and pellet fractions by simple centrifugation. Selected PTYR-containing proteins and p56lck appeared in the pellet fraction as quickly as 5 s after exposure to HgCl2, and were further increased in amount by 5 min. Although the mechanism of triggering these events was redox-linked, the majority of proteins in the Brij 96-insoluble aggregates were dissociated in SDS-PAGE under nonreducing condition. This suggested that PTYR-containing proteins and p56lck themselves do not form dimer or polymer directly by thiol-mediated bond. The pellet fraction was further found to include some other signal delivery elements, such as GTPase activating protein, phosphatidylinositol 3 kinase, and mitogen-activated protein kinase. Finally, all of these signal elements and selected PTYR-containing proteins were collected in the same fraction by the sucrose density gradient centrifugation. These results suggest a unique redox-linked pathway of formation of a giant signal complex.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 55 (1994), S. 264-271 
    ISSN: 0730-2312
    Schlagwort(e): protein kinase C ; transgenic mouse ; dynamics after activation ; prolonged membrane translocation ; disregulation of late signaling ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: Recently, we succeeded in establishing a transgenic mouse line which expressed high levels of protein kinase C (PKC)-alpha in thymocytes at the mRNA level with disproportionately small increases at the protein level. The transgenic PKC-alpha was nevertheless functionally active for inducing accelerated cell growth and IL-2 production by stimulation with anti-receptor (CD3) antibody or phorbol 12-myristate 14-acetate (PMA) in vitro. Study of the dynamics of transgenic PKC-alpha in the cells in vitro showed that the amount of PKC-alpha protein increased in the cells remarkably at ≥ 5 h after stimulation, whereas the level of PKC-alpha mRNA did not change significantly or changed slightly. This suggested that cell activation breaks the posttranscriptional regulation of the transgenic PKC-alpha in resting cells. The increase in PKC-alpha protein accompanied a prolonged membrane translocation of PKC-alpha and enhanced cell proliferation. Such a transgenic effect was inhibited completely by a PKC inhibitor, H-7, added during 0-6 h after the stimulation. These results show formally that the transgenic PKC-alpha whose production was accelerated through cell activation plays a key role in the late (for ≥ 5 h) signal delivery for disregulated cell growth. © 1994 Wiley-Liss, Inc.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 0730-2312
    Schlagwort(e): Src kinase ; mercuric chloride ; redox ; sulfhydryl group ; receptor polymerization ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: Little is known about the regulatory mechanism of c-Src kinase in cells except the suggested regulation through phosphorylation and dephosphorylation of its carboxyl terminal tyrosine residue (Y527). We here demonstrated that exposure of NIH3T3 cells to mercuric chloride (HgCl2) induces both aggregation and activation of Src kinase protein through a redox-linked mechanism. The aggregation of Src proteins was suggested to be induced by the sulfhydryl groups-to-Hg2+ reaction-mediated polymerization of cell membrane proteins to which the Src proteins associate noncovalently. The possibility was ruled out that the aggregation occurred secondarily to the promotion of protein tyrosine phosphorylation. Further study revealed that the Src kinase was activated by HgCl2 at least in part independent of the known Csk kinase-linked or Y527-phosphorylation/dephosphorylation-mediated control. Correspondingly, CNBr cleavage mapping of phosphopeptides for autophosphorylated c-Src protein demonstrated selective promotion of phosphorylation at Y416 in HgCl2-treated cells without obvious change in the phosphorylation level at Y527. These results suggest a unique protein sulfhydryl modification-based pathway of signal transduction for activating Src kinase in NIH3T3 cells. © 1996 Wiley-Liss, Inc.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    ISSN: 0730-2312
    Schlagwort(e): monoiodoacetic acid ; sulfhydryl reagent ; modulation of signal transduction ; redox-linked ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: Actions of monoiodoacetic acid (MIA) as a sulfhydryl reagent on the different stages of the T cell receptor (TCR)-mediated signal transduction were examined. MIA (1 mM) prevented anti-TCR (CD3) monoclonal antibody (mAb)-induced energy-dependent receptor capping but at the same time promoted the anti-CD3 mAb/mitogen-induced tyrosine phosphorylation of the T cell activation-linked cellular proteins of 120, 80, 70, 56, and 40 KDa. Relatively low concentration (0.01 mM) of MIA further promoted anti-CD3 mAb-induced transcription of c-fos, production of IL-2, and cell surface expression of IL-2 receptors. The MIA-promoted TCR-mediated IL-2 production actually required signal transduction that could be inhibited by cyclosporin A, genistein, or H-7. In contrast, the same concentration of MIA as promoted the signal transduction for cell activation severely inhibited the anti-CD3 mAb-triggered signal delivery for cell proliferation, selectively at its early stage. We conclude from these results that MIA differentially affects various steps of signaling into T lymphocytes, suggesting that there exist multiple sites of MIA-sensitive or redox-linked control in the signal cascade. © 1995 Wiley-Liss, Inc.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    ISSN: 0730-2312
    Schlagwort(e): nitric oxide ; SNAP ; Mn-SOD ; inducible NOS ; vascular smooth muscle cells ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: Cultured rat vascular smooth muscle cells (VSMCs) produce nitric oxide (NO) under stimulation by lipopolysaccharide (LPS) and interferon-γ (IFN-γ). NO synthase (NOS) and manganese superoxide dismutase (Mn-SOD) mRNA expressions are simultaneously induced by these stimulants in rat VSMCs. In VSMCs, S-nitroso-N-acetyl penicillamine (SNAP), one of the NO releasing reagents, induces Mn-SOD mRNA which may protect the VSMCs themselves. This suggests that NO itself may enhance the expression of Mn-SOD to protect the VSMC themselves against NO radicals in cultured rat VSMCs. © 1996 Wiley-Liss, Inc.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    ISSN: 0730-2312
    Schlagwort(e): T-lymphocyte ; apoptosis ; signal transduction ; HgCl2 ; tyrosine phosphorylation ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: Exposure to Hg2+ at a wide range of concentrations (approximately 1-100 μM) more or less caused the death of murine thymic T-lymphocytes, and exposure to 1 μM but not 10 μM (or more) of Hg2+ induced DNA fragmentation. Exposure of cells to Hg2+ caused phosphorylation of multiple cellular proteins at the tyrosine residue in a concentration-dependent manner. We found that not only the DNA fragmentation induced by 1 μM Hg2+ but also the cell death bypassing DNA fragmentation caused by 10 μM or more Hg2+ was partly inhibited by protein kinase inhibitors such as staurosporine and herbimycin A. This result suggested the involvement of a protein phosphorylation-linked signal in the mechanism of the Hg2+-mediated cell death with or without DNA fragmentation. Analysis of proteins by both one- and two-dimensional electrophoresis and immunoblot showed that a 52-kDa Shc protein was heavily phosphorylated by an early signal delivered by a high concentration of Hg2+, which also phosphorylated extracellular signal-regulated kinase 1 (ERK1; p44) and ERK2 (p42) of the mitogen-activated protein kinase (MAPK) family in a concentration- and time-dependent manner. The c-Jun amino terminal kinase (p54), which is a distant relative of the MAPK family, was also phosphorylated by the treatment with Hg2+. This eventually formed the signaling cascade that ended with a nuclear target by phosphorylating c-jun at the serine 73. This phosphorylation of c-jun was inhibited by staurosporine. These results suggest that a high level of Hg2+-mediated protein phosphorylation-linked signal induces rapid cell death bypassing DNA fragmentation, whereas a lower level induces cell death accompanying DNA fragmentation. This conclusion in turn implies that DNA fragmentation is not always a prerequisite for the signal transduction-dependent cell death of T-lymphocytes. J. Cell. Biochem. 71:243-253, 1998. © 1998 Wiley-Liss, Inc.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 53 (1993), S. 198-205 
    ISSN: 0730-2312
    Schlagwort(e): nitric oxide ; macrophage cell line ; T lymphocyte stimulation ; feedback suppression ; inflamation site ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: The indirect stimulation of macrophages to produce nitrite was examined by using the macrophage cell line J774. J774 spontaneously produced nitrite, when cultured at high concentration. J774 cultured in low concentration ( 〈 104 cells in 100 μl) barely produced nitrite. J774 cultured in low concentration produced a large amount of nitrite by the co-culture of nonadherent spleen cells or nonadherent peritoneal exudate cells, which were stimulated with con A, anti-CD3, or staphylococcal enterotoxin A. J774 (BALB/c derived: H-2d) cultured with either syngeneic (BALB/c) or allogeneic (B6; H-2b B10BR; H-2k) nonadherent lymphocytes, which were stimulated with conA or anti-CD3, produced nitric oxide. However, J774 produced nitric oxide by stimulation with SEA only when co-cultured with SEA-reactive T lymphocytes. Peritoneal exudate cells from mice, which did not proliferate by the stimulation of conA or anti-CD3, proliferated well by the addition of L-arginine homologue, NG-monomethyl-L-arginine. The proliferation of nonadherent peritoneal exudate cells stimulated with conA or anti-CD3 was suppressed by the addition of peritoneal macrophages. This suppression was abolished by the addition of NG-monomethyl-L-arginine.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 8
    ISSN: 0730-2312
    Schlagwort(e): inducible NOS ; TNF-α ; IL 1-β ; IL-6 ; endotoxemia ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: In this study, we investigated the expression of genes for inducible nitric oxide synthase (iNOS), tumor necrosis factor alpha (TNF-α), interleukin 1β (IL-1β), interleukin 6 (IL-6) of Kupffer cells in the presence of lipopolysaccharide (LPS), and the tissue expression of iNOS in a rat liver after LPS injection at various time intervals. The effects of L-NG-nitroarginine-methyl-esther HCI (L-NAMF), a NO inhibitor, also were examined. The mRNA transcripts of TNF-α IL-1β and IL-6 were rapidly detected no more than at 1 h after LPS stimulation, whereas the iNOS transcript was detectable from 3 h after LPS stimulation and maximally increased at 12 h. This fact suggested that these early induced cytokines were related to expression of iNOS. Using an anti-iNOS antiserum raised against recombinant iNOS protein, immunohistochemical analysis was made to reveal kinetics of NO producing cells. The cells immunoreactive for iNOS appeared at 6 h post-LPS injection in the sinusoids of the liver. By structural and immunohistochemical studies, almost all iNOS positive cells were identified as Kupffer cells and endothelial cells. The number of cells immunoreactive for iNOS increased until 12 h post-LPS injection. At 24 h after LPS injection, iNOS positive cells were restricted to the foci of spotty necrosis. Hepatic injury measured by released enzymes was increased by pretreatment of L-NAME before LPS injection. J. Cell. Biochem. 65:349-358. © 1997 Wiley-Liss, Inc.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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