scholarly journals Involvement of the Ras/extracellular signal-regulated kinase signalling pathway in the regulation of ERCC-1 mRNA levels by insulin

1998 ◽  
Vol 331 (2) ◽  
pp. 591-597 ◽  
Author(s):  
Whaseon LEE-KWON ◽  
Deokbae PARK ◽  
Michel BERNIER
Keyword(s):  
Protein Kinase ◽  
Chinese Hamster Ovary Cells ◽  
Insulin Response ◽  
Chinese Hamster ◽  
Mrna Levels ◽  
Phosphatidylinositol 3 Kinase ◽  
S6 Kinase ◽  
Extracellular Signal ◽  
Dependent Pathway ◽  
Phosphatidylinositol 3

Expression of DNA repair enzymes, which includes ERCC-1, might be under the control of hormonal and growth factor stimulation. In the present study it was observed that insulin increased ERCC-1 mRNA levels both in Chinese hamster ovary cells overexpressing human insulin receptors (HIRc cells) and in fully differentiated 3T3-L1 adipocytes. To investigate the mechanisms underlying the increase in ERCC-1 gene expression in HIRc cells, we used a variety of pharmacological tools known to inhibit distinct signalling pathways. None of these inhibitors affected the amount of ERCC-1 mRNA in unstimulated cells. The pretreatment of cells with two chemically unrelated phosphatidylinositol 3´-kinase inhibitors, wortmannin and LY294002, failed to block the doubling of ERCC-1 mRNA content by insulin. Similarly, inhibition of pp70 S6 kinase by rapamycin had no apparent effects on this insulin response. In contrast, altering the p21ras-dependent pathway with either manumycin, an inhibitor of Ras farnesylation, or PD98059, an inhibitor of the mitogen-activated protein kinase/extracellular signal-regulated protein kinase (ERK) kinase, suppressed the induction of ERCC-1 mRNA by insulin (P< 0.001). Furthermore inhibition of RNA and protein synthesis negatively regulated the expression of this insulin-regulated gene (P< 0.005). These results suggest that insulin enhances ERCC-1 mRNA levels by the activation of the Ras–ERK-dependent pathway without the involvement of the phosphatidylinositol 3´-kinase/pp70 S6 kinase.

Distinct roles for extracellular-signal-regulated protein kinase (ERK) mitogen-activated protein kinases and phosphatidylinositol 3-kinase in the regulation of Mcl-1 synthesis

2001 ◽  
Vol 356 (2) ◽  
pp. 473-480 ◽  
Author(s):  
Kathryn M. SCHUBERT ◽  
Vincent DURONIO
Keyword(s):  
Protein Kinase ◽  
Mapk Pathway ◽  
Family Members ◽  
Protein Translation ◽  
Mitogen Activated Protein Kinase ◽  
Mrna Levels ◽  
Phosphatidylinositol 3 Kinase ◽  
Extracellular Signal ◽  
Mitogen Activated Protein ◽  
Phosphatidylinositol 3

Alterations in the expression of various Bcl-2 family members may act as one means by which a cell's survival may be regulated. The mechanism by which cytokines regulate expression of Bcl-2 family members was examined in the haemopoietic cell line TF-1. Cytokine-induced Mcl-1 protein expression was shown to be controlled through a pathway dependent upon phosphatidylinositol 3-kinase (PI 3-kinase). The cytokine-induced increase in mRNA transcription was not dependent upon PI 3-kinase, thus dissociating the immediate-early transcription factors responsible for Mcl-1 transcription from the PI 3-kinase signalling pathway. In contrast, Mcl-1 mRNA levels were dependent upon MEK [mitogen-activated protein kinase (MAPK)/extracellular-signal-regulated protein kinase kinase] activation, suggesting a role for the Ras/MEK/MAPK pathway in Mcl-1 transcription. Activation of PI 3-kinase was shown to be necessary to stimulate Mcl-1 protein translation. This was not due to any effect on prolonging the half-life of the protein. Finally, the lipid second messenger ceramide was shown to cause a reduction in Mcl-1 protein translation, probably via its ability to inhibit protein kinase B activation, providing further clues regarding the death-inducing effect of this lipid.

scholarly journals Transcriptional regulation of human mucin MUC4 by bile acids in oesophageal cancer cells is promoter-dependent and involves activation of the phosphatidylinositol 3-kinase signalling pathway

2004 ◽  
Vol 377 (3) ◽  
pp. 701-708 ◽  
Author(s):  
Christophe MARIETTE ◽  
Michaël PERRAIS ◽  
Emmanuelle LETEURTRE ◽  
Nicolas JONCKHEERE ◽  
Brigitte HÉMON ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Bile Acids ◽  
Oesophageal Cancer ◽  
Molecular Mechanisms ◽  
Complex Mixture ◽  
Transcriptional Level ◽  
Mrna Levels ◽  
Phosphatidylinositol 3 Kinase ◽  
Mucin Gene ◽  
Phosphatidylinositol 3

Abnormal gastro-oesophageal reflux and bile acids have been linked to the presence of Barrett's oesophageal premalignant lesion associated with an increase in mucin-producing goblet cells and MUC4 mucin gene overexpression. However, the molecular mechanisms underlying the regulation of MUC4 by bile acids are unknown. Since total bile is a complex mixture, we undertook to identify which bile acids are responsible for MUC4 up-regulation by using a wide panel of bile acids and their conjugates. MUC4 apomucin expression was studied by immunohistochemistry both in patient biopsies and OE33 oesophageal cancer cell line. MUC4 mRNA levels and promoter regulation were studied by reverse transcriptase–PCR and transient transfection assays respectively. We show that among the bile acids tested, taurocholic, taurodeoxycholic, taurochenodeoxycholic and glycocholic acids and sodium glycocholate are strong activators of MUC4 expression and that this regulation occurs at the transcriptional level. By using specific pharmacological inhibitors of mitogen-activated protein kinase, phosphatidylinositol 3-kinase, protein kinase A and protein kinase C, we demonstrate that bile acid-mediated up-regulation of MUC4 is promoter-specific and mainly involves activation of phosphatidylinositol 3-kinase. This new mechanism of regulation of MUC4 mucin gene points out an important role for bile acids as key molecules in targeting MUC4 overexpression in early stages of oesophageal carcinogenesis.

Mitogen-activated protein kinase-dependent and -independent routes control shedding of transmembrane growth factors through multiple secretases

2002 ◽  
Vol 363 (2) ◽  
pp. 211-221 ◽  
Author(s):  
Juan Carlos MONTERO ◽  
Laura YUSTE ◽  
Elena DÍAZ-RODRÍGUEZ ◽  
Azucena ESPARÍS-OGANDO ◽  
Atanasio PANDIELLA
Keyword(s):  
Growth Factors ◽  
Protein Kinase ◽  
Uv Light ◽  
Chinese Hamster Ovary Cells ◽  
Chinese Hamster ◽  
Mitogen Activated Protein Kinase ◽  
Ovary Cells ◽  
Extracellular Signal ◽  
Mitogen Activated Protein ◽  
Factor Α

Solubilization of a number of membrane proteins occurs by the action of cell-surface proteases, termed secretases. Recently, the activity of these secretases has been reported to be controlled by the extracellular signal-regulated kinases 1 and 2 (ERK1/ERK2) and the p38 mitogen-activated protein kinase (MAPK) routes. In the present paper, we show that shedding of membrane-anchored growth factors (MAGFs) may also occur through MAPK-independent routes. In Chinese-hamster ovary cells, cleavage induced by protein kinase C (PKC) stimulation was largely insensitive to inhibitors of the ERK1/ERK2 and p38 routes. Other reagents such as sorbitol or UV light stimulated MAGF cleavage independent of PKC. The action of sorbitol on cleavage was only partially prevented by the combined action of inhibitors of the p38 and ERK1/ERK2 routes, indicating that sorbitol can also stimulate shedding by MAPK-dependent and -independent routes. Studies in cells devoid of activity of the secretase tumour necrosis factor-α-converting enzyme (TACE) indicated that this protease had an essential role in PKC- and ERK1/ERK2-mediated shedding. However, secretases other than TACE may also cleave MAGFs since sorbitol could still induce shedding in these cells. These observations suggest that cleavage of MAGFs is a complex process in which multiple secretases, activated through different MAPK-dependent and -independent routes, are involved.

Activation of phosphatidylinositol 3-kinase is required for transcriptional activity of F-type 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase: assessment of the role of protein kinase B and p70 S6 kinase

2000 ◽  
Vol 349 (1) ◽  
pp. 59-65 ◽  
Author(s):  
Silvia FERNÁNDEZ DE MATTOS ◽  
Elisabet DE LOS PINOS ◽  
Manel JOAQUIN ◽  
Albert TAULER
Keyword(s):  
Gene Expression ◽  
Protein Kinase ◽  
Transcriptional Activity ◽  
Protein Kinase B ◽  
Dominant Negative ◽  
Phosphatidylinositol 3 Kinase ◽  
S6 Kinase ◽  
Dominant Negative Form ◽  
Negative Form ◽  
Phosphatidylinositol 3

Previous studies have demonstrated that the F isoform of 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase(6PF2K/Fru-2,6-BPase) is transcriptionally regulated by growth factors. The aim of this study was to investigate the importance of the phosphatidylinositol 3-kinase (PI 3-kinase) pathway in the regulation of 6PF2K/Fru-2,6-BPase gene expression. We have completed studies using chemical inhibitors and expression vectors for the proteins involved in this signalling cascade. Treatment of cells with LY 294002, an inhibitor of PI 3-kinase, blocked the epidermal growth factor (EGF)-dependent stimulation of 6PF2K/Fru-2,6-BPase gene transcription. Transient transfection of a constitutively active PI 3-kinase was sufficient to activate transcription from the F-type 6PF2K/Fru-2,6-BPase promoter. In contrast, co-transfection with a dominant-negative form of PI 3-kinase completely abrogated the stimulation by EGF, and down-regulated the basal promoter activity. In an attempt to determine downstream proteins that lie between PI 3-kinase and 6PF2K/Fru-2,6-BPase gene expression, the overexpression of a constitutively active form of protein kinase B (PKB) was sufficient to activate 6PF2K/Fru-2,6-BPase gene expression, even in the presence of either a dominant-negative form of PI 3-kinase or LY 294002. The over-expression of p70/p85 ribosomal S6 kinase or the treatment with its inhibitor rapamycin did not affect 6PF2K/Fru-2,6-BPase transcription. We conclude that PI 3-kinase is necessary for the transcriptional activity of F-type 6PF2K/Fru-2,6-BPase, and that PKB is a downstream effector of PI 3-kinase directly involved in the regulation of 6PF2K/Fru-2,6-BPase gene expression.

scholarly journals Insulin can block apoptosis by decreasing oxidative stress via phosphatidylinositol 3-kinase- and extracellular signal-regulated protein kinase-dependent signaling pathways in HepG2 cells

2003 ◽  
pp. 147-155 ◽  
Author(s):  
S Kang ◽  
J Song ◽  
H Kang ◽  
S Kim ◽  
Y Lee ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Protein Kinase ◽  
Signaling Pathways ◽  
Hepg2 Cells ◽  
Caspase 3 ◽  
Pi3 Kinase ◽  
Phosphatidylinositol 3 Kinase ◽  
Extracellular Signal ◽  
Apoptotic Activity ◽  
Phosphatidylinositol 3

OBJECTIVE: Insulin has well-known activities in controlling energy metabolism, cellular proliferation and biosynthesis of functional molecules to maintain a biological homeostasis. Recently, several studies have suggested that insulin may protect cells from apoptosis in different cell lines; however, little is known about the nature of its anti-apoptotic activity. In many clinical disorders, including type 2 diabetes mellitus, oxidative stress and the production of reactive oxygen species (ROS) is increased. With these facts as a background, we examined here whether insulin protects HepG2 cells from apoptosis by decreasing oxidative stress and, if so, which signaling steps are involved in this process. METHODS: Intracellular DNA content, the degree of nuclear condensation or poly(ADP-ribose) polymerase hydrolysis was measured to verify the occurrence of apoptotic events. Caspase-3 activity and ROS accumulation within cells were also measured. Western blot analysis was performed to identify signaling molecules activated in response to insulin. RESULTS: Serum starvation resulted in a marked accumulation of ROS, activation of caspase-3, and subsequent apoptotic cell death which were, in turn, markedly blocked by the addition of insulin. The anti-apoptotic activity of insulin was sensitive to blockade of two different signaling steps, activations of phosphatidylinositol 3-kinase (PI3 kinase) and extracellular signal-regulated protein kinase (ERK). CONCLUSION: Insulin exerts an anti-apoptotic activity by suppressing the excessive accumulation of ROS within cells through signaling pathways including stimulation of PI3 kinase and ERK in HepG2 cells.

scholarly journals Na/H Exchange Regulatory Factor 1, a Novel AKT-associating Protein, Regulates Extracellular Signal-regulated Kinase Signaling through a B-Raf–Mediated Pathway

2008 ◽  
Vol 19 (4) ◽  
pp. 1637-1645 ◽  
Author(s):  
Bin Wang ◽  
Yanmei Yang ◽  
Peter A. Friedman
Keyword(s):  
Parathyroid Hormone ◽  
Protein Kinase ◽  
Chinese Hamster Ovary Cells ◽  
Chinese Hamster ◽  
Scaffolding Protein ◽  
Inhibitory Influence ◽  
Adapter Proteins ◽  
Regulatory Factor ◽  
Extracellular Signal Regulated Kinase ◽  
Extracellular Signal

Na/H exchange regulatory factor 1 (NHERF1) is a scaffolding protein that regulates signaling and trafficking of several G protein-coupled receptors (GPCRs), including the parathyroid hormone receptor (PTH1R). GPCRs activate extracellular signal-regulated kinase (ERK)1/2 through different mechanisms. Here, we characterized NHERF1 regulation of PTH1R-stimulated ERK1/2. Parathyroid hormone (PTH) stimulated ERK1/2 phosphorylation by a protein kinase A (PKA)-dependent, but protein kinase C-, cyclic adenosine 5′-monophosphate-, and Rap1-independent pathway in Chinese hamster ovary cells stably transfected with the PTH1R and engineered to express NHERF1 under the control of tetracycline. NHERF1 blocked PTH-induced ERK1/2 phosphorylation downstream of PKA. This suggested that NHERF1 inhibitory effects on ERK1/2 occur at a postreceptor locus. Forskolin activated ERK1/2, and this effect was blocked by NHERF1. NHERF1 interacted with AKT and inhibited ERK1/2 activation by decreasing the stimulatory effect of 14-3-3 binding to B-Raf, while increasing the inhibitory influence of AKT negative regulation on ERK1/2 activation. This novel regulatory mechanism provides a new model by which cytoplasmic adapter proteins modulate ERK1/2 activation through a receptor-independent mechanism involving B-Raf.

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