scholarly journals Growth Factor-Independent Proliferation of Erythroid Cells Infected with Friend Spleen Focus-Forming Virus Is Protein Kinase C Dependent but Does Not Require Ras-GTP

2000 ◽  
Vol 74 (18) ◽  
pp. 8444-8451 ◽  
Author(s):  
Karen W. Muszynski ◽  
Delores Thompson ◽  
Charlotte Hanson ◽  
Rebecca Lyons ◽  
Angelo Spadaccini ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Mapk Pathway ◽  
Viral Envelope ◽  
Cell Surface Receptor ◽  
Signal Transduction Pathways ◽  
Erythroid Cells ◽  
Kinase C ◽  
Infected Cells

ABSTRACT Interaction of erythropoietin (Epo) with its cell surface receptor activates signal transduction pathways which result in the proliferation and differentiation of erythroid cells. Infection of erythroid cells with the Friend spleen focus-forming virus (SFFV) leads to the interaction of the viral envelope glycoprotein with the Epo receptor and renders these cells Epo independent. We previously reported that SFFV induces Epo independence by constitutively activating components of several Epo signal transduction pathways, including the Jak-Stat and the Raf-1/mitogen-activated protein kinase (MAPK) pathways. To further evaluate the mechanism by which SFFV activates the Raf-1/MAPK pathway, we investigated the effects of SFFV on upstream components of this pathway, and our results indicate that SFFV activates Shc and Grb2 and that this leads to Ras activation. While studies with a dominant-negative Ras indicated that Ras was required for Epo-induced proliferation of normal erythroid cells, the Epo-independent growth of SFFV-infected cells can still occur in the absence of Ras, although at reduced levels. In contrast, protein kinase C (PKC) was shown to be required for the Epo-independent proliferation of SFFV-infected cells. Further studies indicated that PKC, which is thought to be involved in the activation of both Raf-1 and MAPK, was required only for the activation of MAPK, not Raf-1, in SFFV-infected cells. Our results indicate that Ras and PKC define two distinct signals converging on MAPK in both Epo-stimulated and SFFV-infected erythroid cells and that activation of only PKC is sufficient for the Epo-independent proliferation of SFFV-infected cells.

Two Interacting Signal Transduction Pathways Regulate Collecting Duct Water Transport

Physiology ◽  
1988 ◽  
Vol 3 (6) ◽  
pp. 235-241 ◽  
Author(s):  
Y Ando ◽  
HR Jacobson ◽  
MD Breyer
Keyword(s):  
Signal Transduction ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Cyclic Amp ◽  
Cell Function ◽  
Collecting Duct ◽  
Signal Transduction Pathways ◽  
Phosphatidylinositol Bisphosphate ◽  
Kinase C ◽  
Arachidonate Metabolites

Receptor-mediated signal transduction occurs through phosphatidylinositol bisphosphate (PIP2) breakdown and activation of adenylate cyclase interacting to regulate cell function. Current studies suggest that hormone-stimulated PIP2 breakdown modulates the classic cyclic AMP-mediated hydrosmotic action of vasopressin through separate mechanisms attributable to activation of protein kinase C, elevation of intracellular Ca2+ concentration, and generation of arachidonate metabolites.

HC fragment (C-terminal portion of the heavy chain) of tetanus toxin activates protein kinase C isoforms and phosphoproteins involved in signal transduction

2001 ◽  
Vol 356 (1) ◽  
pp. 97-103 ◽  
Author(s):  
Carles GIL ◽  
Imane CHAIB-OUKADOUR ◽  
Juan BLASI ◽  
José AGUILERA
Keyword(s):  
Signal Transduction ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Tyrosine Phosphorylation ◽  
Heavy Chain ◽  
Tetanus Toxin ◽  
Signal Transduction Pathways ◽  
Terminal Portion ◽  
Kinase C ◽  
Pkc Isoforms

A recent report [Gil, Chaib-Oukadour, Pelliccioni and Aguilera (2000) FEBS Lett. 481, 177–182] describes activation of signal transduction pathways by tetanus toxin (TeTx), a Zn2+-dependent endopeptidase synthesized by the Clostridium tetani bacillus, which is responsible for tetanus disease. In the present work, specific activation of protein kinase C (PKC) isoforms and of intracellular signal-transduction pathways, which include nerve-growth-factor (NGF) receptor trkA, phospholipase C(PLC)γ-1 and extracellular regulated kinases (ERKs) 1 and 2, by the recombinant C-terminal portion of the TeTx heavy chain (HC-TeTx) is reported. The activation of PKC isoforms was assessed through their translocation from the soluble (cytosolic) compartment to the membranous compartment, showing that clear translocation of PKC-α, −β, −γ and −δ isoforms exists, whereas PKC-∊ showed a slight decrease in its soluble fraction immunoreactivity. The PKC-∊ isoform showed no consistent response. Using immunoprecipitation assays against phosphotyrosine residues, time- and dose-dependent increases in tyrosine phosphorylation were observed in the trkA receptor, PLCγ-1 and ERK-1/2. The effects shown by the HC-TeTx fragment on tyrosine phosphorylation were compared with the effects produced by NGF. The trkA and ERK-1/2 activation were corroborated using phospho-specific antibodies against trkA phosphorylated on Tyr490, and antibodies against Thr/Tyr phosphorylated ERK-1/2. Moreover, PLCγ-1 phosphorylation was supported by its HC-TeTx-induced translocation to the membranous compartment, an event related to PLCγ-1 activation. Since HC-TeTx is the domain responsible for membrane binding and lacks catalytic activity, the activations described here must be exclusively triggered by the interaction of TeTx with a membrane component.

Differential expression of early response genes, c-jun, c-fos, and jun B, in A5 cells

1992 ◽  
Vol 263 (6) ◽  
pp. G934-G938 ◽  
Author(s):  
C. K. Yeh ◽  
I. S. Ambudkar ◽  
E. Kousvelari
Keyword(s):  
Signal Transduction ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Early Response ◽  
Signal Transduction Pathways ◽  
Epithelial Cell Line ◽  
Mrna Levels ◽  
Serum Factors ◽  
Kinase C ◽  
Jun B

We examined the expression of c-fos, c-jun, and jun B after activation of different signal transduction pathways in the A5 rat salivary epithelial cell line. Stimulation of beta-adrenergic receptors by isoproterenol, or addition of 8-bromoadenosine 3',5'-cyclic monophosphate, induces the expression of c-fos and jun B by a protein kinase A-mediated pathway. Phorbol 12-myristate 13-acetate (PMA) induces the expression of all three genes, but with different kinetics. While c-fos and jun B mRNA levels increase early (1 h) after stimulation and transiently, those of c-jun remain higher than control even after stimulation for 8 h and return to basal levels by 24 h. Inhibitors of protein kinase C block the effect of PMA on c-fos, c-jun, and jun B expression, indicating that these genes are also regulated by a protein kinase C-mediated mechanism in A5 cells. Increases in cytosolic Ca2+ by A23187 or ionomycin induce only the expression of c-fos gene. This induction is abolished when A5 cells are loaded with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid before treatment with the ionophores, or when serum is excluded from the incubation medium. Exclusion of serum from the medium does not change the effects of isoproterenol or PMA on c-fos, c-jun, or jun B. These results strongly suggest that serum factors act synergistically with Ca2+ to induce c-fos expression in A5 cells. The studies presented here indicate that different signal transduction pathways operate in A5 cells for the induction of c-fos, c-jun, and jun B genes.

scholarly journals Interleukin 1-β-induced protein kinase C-ζ activation is mimicked by exogenous phospholipase D

1997 ◽  
Vol 321 (2) ◽  
pp. 497-502 ◽  
Author(s):  
Cristina LIMATOLA ◽  
Benedetta BARABINO ◽  
Anna NISTA ◽  
Angela SANTONI
Keyword(s):  
Signal Transduction ◽  
Protein Kinase C ◽  
Protein Kinase ◽  
Phosphatidic Acid ◽  
Phospholipase D ◽  
Biological Effects ◽  
Interleukin 1 ◽  
Signal Transduction Pathways ◽  
Kinase C ◽  
Pkc Ζ

Interleukin 1-α (IL1-α) is a pleiotropic cytokine that stimulates a number of signal transduction pathways in cells, leading to different cellular responses. In this study we investigated the signal transduction pathways activated by IL1-α in two different human cell lines: RD/TE671, a rhabdomyosarcoma, and EJ, a bladder-derived carcinoma. We showed that this cytokine induced the activation of protein kinase C-ζ (PKC-ζ) and the accumulation of a putative physiological PKC-ζ activator, phosphatidic acid [Limatola, Schaap, Moolenaar and van Blitterswijk (1994) Biochem. J. 304, 1001Ő1008]. Exogenously supplied phospholipase D, which generated cellular phosphatidic acid, was able to mimic the cytokine effect, supporting the hypothesis that this lipid second messenger might contribute to cytokine-induced PKC-ζ activation. In addition, we show that IL1-α stimulation of BOSC23 cells, transiently overexpressing PKC-ζ, induced an increase in PKC-ζ autophosphorylation. These results give the first direct evidence that IL1-α can activate this atypical PKC isoform and suggest that this enzyme might be involved in mediating some of the biological effects induced by IL1-α.

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