Phospholipase D Signaling and Extracellular Signal-Regulated Kinase-1 and -2 Phosphorylation (Activation) Are Required for Maximal Phorbol Ester-Induced Transglutaminase Activity, a Marker of Keratinocyte Differentiation

2004 ◽  
Vol 312 (3) ◽  
pp. 1223-1231 ◽  
Author(s):  
Wendy B. Bollag ◽  
Xiaofeng Zhong ◽  
M. Ernest Dodd ◽  
David M. Hardy ◽  
Xiangjian Zheng ◽  
...  
1995 ◽  
Vol 306 (3) ◽  
pp. 723-726 ◽  
Author(s):  
N Moughal ◽  
P A Stevens ◽  
D Kong ◽  
S Pyne ◽  
N J Pyne

Bradykinin and phorbol 12-myristate 13-acetate stimulate adenylate cyclase activity in serum-depleted cultured airway smooth muscle via a protein kinase C (PKC)-dependent pathway. The probable target is the type II adenylate cyclase, which can integrate coincident signals from both PKC and Gs. Therefore, activation of Gs (by cholera-toxin pre-treatment) amplified the bradykinin-stimulated cyclic AMP signal and concurrently attenuated the partial activation of extracellular-signal-regulated kinase-2 (ERK-2) by bradykinin. We have previously demonstrated that, in order to induce full activation of ERK-2 with bradykinin, it is necessary to obliterate PKC-stimulated cyclic AMP formation. We concluded that the cyclic AMP signal limits the magnitude of ERK-2 activation [Pyne, Moughal, Stevens, Tolan and Pyne (1994) Biochem. J. 304, 611-616]. The present study indicates that the bradykinin-stimulated ERK-2 pathway is entirely cyclic AMP-sensitive, and suggests that coincident signal detection by adenylate cyclase may be an important physiological route for the modulation of early mitogenic signalling. Furthermore, the direct inhibition of adenylate cyclase activity enables bradykinin to induce DNA synthesis, indicating that the PKC-dependent activation of adenylate cyclase limits entry of cells into the cell cycle. These studies suggest that the mitogenicity of an agonist may be governed, in part, by its ability to stimulate an inhibitory cyclic AMP signal pathway in the cell. The activation of adenylate cyclase by PKC appears to be downstream of phospholipase D. However, in cells that were maintained in growth serum (i.e. were not growth-arrested), bradykinin was unable to elicit a PKC-stimulated cyclic AMP response. The lesion in the signal-response coupling was not at the level of either the receptor or phospholipase D, which remain functionally operative and suggests modification occurs at either PKC or adenylate cyclase itself. These studies are discussed with respect to the cell signal regulation of mitogenesis in airway smooth muscle.


2001 ◽  
Vol 357 (3) ◽  
pp. 867-873 ◽  
Author(s):  
Dieter SCHMOLL ◽  
Rolf GREMPLER ◽  
Andreas BARTHEL ◽  
Hans-Georg JOOST ◽  
Reinhard WALTHER

Glucose-6-phosphatase (G6Pase) plays a central role in blood glucose homoeostasis, and insulin suppresses G6Pase gene expression by the activation of phosphoinositide 3-kinase (PI 3-kinase). Here, we show that the phorbol ester PMA decreases both basal and dexamethasone/cAMP-induced expression of a luciferase gene under the control of the G6Pase promoter in transiently transfected H4IIE hepatoma cells. This regulation was suppressed by the inhibitors of the mitogen-activated protein kinase/extracellular-signal-regulated kinase kinase (MEK), PD98059 and U0126, but not by the inhibitor of PI 3-kinase, LY294002. The co-expression of a constitutively active mutant of MEK mimicked the regulation of G6Pase promoter activity by PMA. The effect of PMA on both basal and induced G6Pase gene transcription was impaired by the overexpression of a dominant negative MEK construct, as well as by the expression of mitogen-activated protein kinase phosphatase-1. The mutation of the forkhead-binding sites within the insulin-response unit of the G6Pase promoter, which decreases the effect of insulin on G6Pase gene expression, did not alter the regulation of gene expression by PMA. The data show that PMA decreases G6Pase gene expression by the activation of MEK and extracellular-signal regulated protein kinase. With that, PMA mimics the effect of insulin on G6Pase gene expression by a different signalling pathway.


2002 ◽  
Vol 362 (3) ◽  
pp. 665-674 ◽  
Author(s):  
Mini P. SAJAN ◽  
Gautam BANDYOPADHYAY ◽  
Yoshinori KANOH ◽  
Mary L. STANDAERT ◽  
Michael J. QUON ◽  
...  

Sorbitol, ‘osmotic stress’, stimulates GLUT4 glucose transporter translocation to the plasma membrane and glucose transport by a phosphatidylinositol (PI) 3-kinase-independent mechanism that reportedly involves non-receptor proline-rich tyrosine kinase-2 (PYK2) but subsequent events are obscure. In the present study, we found that extracellular signal-regulated kinase (ERK) pathway components, growth-factor-receptor-bound-2 protein, son of sevenless (SOS), RAS, RAF and mitogen-activated protein (MAP) kinase/ERK kinase, MEK(−1), operating downstream of PYK2, were required for sorbitol-stimulated GLUT4 translocation/glucose transport in rat adipocytes, L6 myotubes and 3T3/L1 adipocytes. Furthermore, sorbitol activated atypical protein kinase C (aPKC) through a similar mechanism depending on the PYK2/ERK pathway, independent of PI 3-kinase and its downstream effector, 3-phosphoinositide-dependent protein kinase-1 (PDK-1). Like PYK2/ERK pathway components, aPKCs were required for sorbitol-stimulated GLUT4 translocation/glucose transport. Interestingly, sorbitol stimulated increases in phospholipase D (PLD) activity and generation of phosphatidic acid (PA), which directly activated aPKCs. As with aPKCs and glucose transport, sorbitol-stimulated PLD activity was dependent on the ERK pathway. Moreover, PLD-generated PA was required for sorbitol-induced activation of aPKCs and GLUT4 translocation/glucose transport. Our findings suggest that sorbitol sequentially activates PYK2, the ERK pathway and PLD, thereby increasing PA, which activates aPKCs and GLUT4 translocation. This mechanism contrasts with that of insulin, which primarily uses PI 3-kinase, D3-PO4 polyphosphoinositides and PDK-1 to activate aPKCs.


2002 ◽  
Vol 283 (1) ◽  
pp. C251-C260 ◽  
Author(s):  
Philippe Robin ◽  
Isaline Boulven ◽  
Christine Desmyter ◽  
Simone Harbon ◽  
Denis Leiber

In this study, we analyzed in rat myometrial cells the signaling pathways involved in the endothelin (ET)-1-induced extracellular signal-regulated kinase (ERK) activation required for the induction of DNA synthesis. We found that inhibition of protein kinase C (PKC) by Ro-31–8220 abolished ERK activation. Inhibition of phospholipase C (PLC) by U-73122 or of phosphoinositide (PI) 3-kinase by wortmannin partially reduced ERK activation. A similar partial inhibition was observed after treatment with pertussis toxin or PKC downregulation by phorbol ester treatment. The effect of wortmannin was additive with that produced by PKC downregulation but not with that due to pertussis toxin. These results suggest that both diacylglycerol-sensitive PKC, activated by PLC products, and diacylglycerol-insensitive PKC, possibly activated by a Gi-PI 3-kinase-dependent process, are involved in ET-1-induced ERK activation. These two pathways were found to be activated mainly through the ETA receptor subtype. ET-1 and phorbol ester stimulated Src activity in a PKC-dependent manner, both responses being abolished in the presence of Ro-31–8220. Inhibition of Src kinases by PP1 abrogated phorbol ester- and ET-1-induced ERK activation. Finally, ET-1 activated Ras in a PP1- and Ro-31–8220-sensitive manner. Altogether, our results indicate that ET-1 induces ERK activation in rat myometrial cells through the sequential stimulation of PKC, Src, and Ras.


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