Phosphorylation of p38 Mitogen-Activated Protein Kinase Downstream of Bax-Caspase-3 Pathway Leads to Cell Death Induced by High d-Glucose in Human Endothelial Cells

Thrombin signaling in endothelial cells provides an important link between coagulation and inflammation. We report here that thrombin induces endogenous Egr-1 mRNA and Egr-1 promoter activity in primary human endothelial cells by approximately 6-fold and 3-fold, respectively. In transient transfection assays, deletion of the 3′ cluster of serum response elements (SREs), but not the 5′ cluster of SREs, resulted in a loss of thrombin response. When coupled to a heterologous core promoter, a region spanning the 3′ SRE cluster contained information for thrombin response, whereas a region spanning the 5′ SRE cluster had no such effect. A point mutation of the most proximal SRE (SRE-1), but not of the proximal Ets motif or upstream SREs, abrogated the response to thrombin. In electrophoretic mobility shift assays, nuclear extracts from thrombin-treated cells displayed increased binding of total and phosphorylated serum response factor (SRF) to SRE-1. Thrombin-mediated induction of Egr-1 was blocked by inhibitors of MEK1/2, but not by inhibitors of protein kinase C, phosphatidylinositol 3-kinase, or p38 mitogen-activated protein kinase (MAPK). Taken together, these data suggest that thrombin induces Egr-1 expression in endothelial cells by a MAPK-dependent mechanism that involves an interaction between SRF and SRE-1.

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Involvement of the Mitogen-activated Protein Kinase Family in Tetracaine-induced PC12 Cell Death

Anesthesiology ◽

10.1097/00000542-200205000-00024 ◽

2002 ◽

Vol 96 (5) ◽

pp. 1191-1201 ◽

Cited By ~ 35

Author(s):

Zhiming Tan ◽

Shuji Dohi ◽

Jinen Chen ◽

Yosiko Banno ◽

Yoshinori Nozawa

Keyword(s):

Cell Death ◽

Protein Kinase ◽

Pc12 Cells ◽

Dna Fragmentation ◽

Local Anesthetics ◽

Caspase 3 ◽

Mitogen Activated Protein Kinase ◽

Dependent Manner ◽

Erk Phosphorylation ◽

Mitogen Activated Protein

Background To explore whether cytotoxicity of local anesthetics is related to apoptosis, the authors examined how local anesthetics affect mitogen-activated protein kinase (MAPK) family members, extracellular signal-regulated kinases (ERKs), c-Jun N-terminal kinases (JNKs)-stress-activated protein kinases, and p38 kinase, which are known to play important roles in apoptosis. Methods Cell death was evaluated using PC12 cells. Morphologic changes of cells, cellular membrane, and nuclei were observed. DNA fragmentation was electrophoretically assayed. Western blot analysis was performed to analyze phosphorylation of the MAPK family, cleavage of caspase-3 and poly(adenosine diphosphate-ribose) polymerase. Intracellular Ca2+ concentration was measured using a calcium indicator dye. Results Tetracaine-induced cell death was shown in a time- and concentration-dependent manner and characterized by nuclear condensation or fragmentation, membrane blebbing, and internucleosomal DNA fragmentation. Caspase-3 activation and phosphorylation of ERK, JNK, and p38 occurred in the cell death. PD98059, an inhibitor of ERK, enhanced tetracaine-induced cell death and JNK phosphorylation, whereas ERK phosphorylation was inhibited. Curcumin, an inhibitor of JNK pathway, attenuated the cell death. Increase of intracellular Ca2+ concentration was detected. In addition to the increase of ERK phosphorylation and the decrease of JNK phosphorylation, two Ca2+ chelators protected cells from death. Neither cell death nor phosphorylation of the MAPK family was caused by tetrodotoxin. Nifedipine did not affect tetracaine-induced apoptosis. Conclusions Tetracaine induces apoptosis of PC12 cells via the MAPK family. ERK activation protects cells from death, but JNK plays the opposite role. Toxic Ca2+ influx caused by tetracaine seems to be responsible for the cell death, but blocking of Na+ channels or L-type Ca2+ channels is unlikely involved in the tetracaine's action for apoptosis.

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