scholarly journals Differential Activation of p38 Mitogen-activated Protein Kinase and Extracellular Signal-regulated Protein Kinases Confers Cadmium-induced HSP70 Expression in 9L Rat Brain Tumor Cells

1998 ◽  
Vol 273 (48) ◽  
pp. 31924-31931 ◽  
Author(s):  
Jan-Jong Hung ◽  
Ting-Jen Cheng ◽  
Yiu-Kay Lai ◽  
Margaret Dah-Tsyr Chang
Keyword(s):  
Brain Tumor ◽  
Protein Kinase ◽  
Tumor Cells ◽  
Protein Kinases ◽  
Mitogen Activated Protein Kinase ◽  
Hsp70 Expression ◽  
Brain Tumor Cells ◽  
Extracellular Signal ◽  
Rat Brain Tumor ◽  
Mitogen Activated Protein

scholarly journals Activation of Extracellular Signal-Related Protein Kinases 1 and 2 of the Mitogen-Activated Protein Kinase Family by Lipopolysaccharide Requires Plasma in Neutrophils from Adults and Newborns

2001 ◽  
Vol 69 (5) ◽  
pp. 3143-3149 ◽  
Author(s):  
S. Bonner ◽  
S. R. Yan ◽  
D. M. Byers ◽  
R. Bortolussi
Keyword(s):  
Protein Kinase ◽  
Protein Kinases ◽  
Oxidative Burst ◽  
Mitogen Activated Protein Kinase ◽  
Related Protein ◽  
Extracellular Signal ◽  
Oxidative Response ◽  
Mitogen Activated Protein ◽  
Mediated Priming

ABSTRACT Neutrophils exposed to low concentrations of gram-negative lipopolysaccharide (LPS) become primed and have an increased oxidative response to a second stimulus (e.g., formyl-methionyl-leucyl-phenylalanine [fMLP]). In studies aimed at understanding newborn sepsis, we have shown that neutrophils of newborns are not primed in response to LPS. To further understand the processes involved in LPS-mediated priming of neutrophils, we explored the role of extracellular signal-related protein kinases (ERK 1 and 2) of the mitogen-activated protein kinase family. We found that LPS activated ERK 1 and 2 in cells of both adults and newborns and that activation was plasma dependent (maximal at ≥5%) through LPS-binding protein. Although fibronectin in plasma is required for LPS-mediated priming of neutrophils of adults assessed by fMLP-triggered oxidative burst, it was not required for LPS-mediated activation of ERK 1 and 2. LPS-mediated activation was dose and time dependent; maximal activation occurred with approximately 5 ng of LPS per ml and at 10 to 40 min. We used the inhibitor PD 98059 to study the role of ERK 1 and 2 in the LPS-primed fMLP-triggered oxidative burst. While Western blotting showed that 100 μM PD 98059 completely inhibited LPS-mediated ERK activation, oxidative response to fMLP by a chemiluminescence assay revealed that the same concentration inhibited the LPS-primed oxidative burst by only 40%. We conclude that in neutrophils, LPS-mediated activation of ERK 1 and 2 requires plasma and that this activation is not dependent on fibronectin. In addition, we found that the ERK pathway is not responsible for the lack of LPS priming in neutrophils of newborns but may be required for 40% of the LPS-primed fMLP-triggered oxidative burst in cells of adults.

Sunitinib inhibits catecholamine synthesis and secretion in pheochromocytoma tumor cells by blocking VEGF receptor 2 via PLC-γ-related pathways

2012 ◽  
Vol 303 (8) ◽  
pp. E1006-E1014 ◽  
Author(s):  
Yuichi Aita ◽  
Kiyo-aki Ishii ◽  
Yuria Saito ◽  
Tatsuhiko Ikeda ◽  
Yasushi Kawakami ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Tumor Cells ◽  
Mitogen Activated Protein Kinase ◽  
Catecholamine Secretion ◽  
Dependent Manner ◽  
Catecholamine Synthesis ◽  
Extracellular Signal Regulated Kinase ◽  
Pc 12 Cells ◽  
Extracellular Signal ◽  
Mitogen Activated Protein

Sunitinib is an oral, small molecule multitargeted receptor tyrosine kinase inhibitor with antiangiogenic and antitumor activity that primarily targets vascular endothelial growth factor receptors (VEGFRs). Although sunitinib is an active agent for the treatment of malignant pheochromocytomas, it is unclear whether sunitinib acts through only antiangiogenic mechanisms or also directly targets tumor cells. We previously showed that sunitinib directly induced apoptosis of PC-12 cells. To further confirm these direct effects, we examined the effects of sunitinib on tyrosine hydroxylase (TH) (the rate-limiting enzyme in catecholamine biosynthesis) activity and catecholamine secretion in PC-12 cells and the underlying mechanisms. Sunitinib inhibited TH activity in a dose-dependent manner, and decreased TH protein levels. Consistent with this finding, sunitinib decreased TH phosphorylation at Ser31 and Ser40 and significantly decreased catecholamine secretion. VEGFR-2 knockdown attenuated these effects, including inhibition of TH activity and catecholamine secretion, suggesting that they were mediated by VEGFR-2. Sunitinib significantly decreased phospholipase C (PLC)-γ phosphorylation and subsequent protein kinase C (PKC) activity. Because Ser40 phosphorylation significantly affects TH activity and is known to be regulated by PKC, sunitinib may inhibit Ser40 phosphorylation via the VEGFR-2/PLC-γ/PKC pathway. Additionally, sunitinib markedly decreased the activity of extracellular signal-regulated kinase (ERK), but not c-Jun NH2-terminal kinase or p38 mitogen-activated protein kinase. Therefore, sunitinib may reduce TH Ser31 phosphorylation through inhibition of the VEGFR-2/PLC-γ/PKC/Raf/mitogen-activated protein kinase/extracellular signal-regulated kinase kinase/ERK pathway. Sunitinib also significantly reduced inositol 1,4,5-trisphosphate production. However, because PC-12 cells do not precisely reflect the pathogenesis of malignant cells, we confirmed the key findings in a human neuroblastoma cell line, SK-N-SH. In conclusion, sunitinib directly inhibits catecholamine synthesis and secretion in pheochromocytoma PC-12 cells.

scholarly journals Activation of the extracellular signal-regulated kinase by complement C5b-9

2005 ◽  
Vol 289 (3) ◽  
pp. F593-F603 ◽  
Author(s):  
Andrey V. Cybulsky ◽  
Tomoko Takano ◽  
Joan Papillon ◽  
Krikor Bijian ◽  
Julie Guillemette
Keyword(s):  
Protein Kinase ◽  
Actin Cytoskeleton ◽  
Protein Kinases ◽  
Mitogen Activated Protein Kinase ◽  
Glomerular Epithelial Cell ◽  
Erk Activation ◽  
Extracellular Signal Regulated Kinase ◽  
Extracellular Signal ◽  
Mitogen Activated Protein ◽  
Constitutively Active

Extracellular signals may be transmitted to nuclear or cytoplasmic effectors via the mitogen-activated protein kinases. In the passive Heymann nephritis (PHN) model of membranous nephropathy, complement C5b-9 induces glomerular epithelial cell (GEC) injury, proteinuria, and activation of phospholipases and protein kinases. This study addresses the complement-mediated activation of the extracellular signal-regulated kinase (ERK). C5b-9 induced ERK threonine202/tyrosine204 phosphorylation (which correlates with activation) in GEC in culture and PHN in vivo. Expression of a dominant-inhibitory mutant of Ras reduced complement-mediated activation of ERK, but activation was not affected significantly by downregulation of protein kinase C. Complement-induced ERK activation resulted in phosphorylation of cytosolic phospholipase A2 and was, in part, responsible for phosphorylation of mitogen-activated protein kinase-associated protein kinase-2, but did not induce phosphorylation of the transcription factor, Elk-1. Activation of ERK was attenuated by drugs that disassemble the actin cytoskeleton (cytochalasin D, latrunculin B), and these compounds interfered with the activation of ERK by mitogen-activated protein kinase kinase (MEK). Overexpression of a constitutively active RhoA as well as inhibition of Rho-associated kinase blocked complement-mediated ERK activation. Complement cytotoxicity was enhanced after disassembly of the actin cytoskeleton but was unaffected after inhibition of complement-induced ERK activation. However, complement cytotoxicity was enhanced in GEC that stably express constitutively active MEK. Thus complement-induced ERK activation depends on cytoskeletal remodelling and affects the regulation of distinct downstream substrates, while chronic, constitutive ERK activation exacerbates complement-mediated GEC injury.

Sign in / Sign up

Export Citation Format

Share Document