Apoptosis signal-regulating kinase 1-mediated signaling pathway regulates hydrogen peroxide-induced apoptosis in human pulmonary vascular endothelial cells.

Objective: Reactive oxygen species initiate pulmonary vascular endothelial cell damage leading to an increase in endothelial permeability resulting in the production of pulmonary edema. Apoptosis signal-regulating kinase (ASK)-1 is a ubiquitously expressed mitogen-activated protein kinase kinase kinase (MAPKKK) that activates the MKK3/MKK6-p38 MAPK and the SEK1-c-Jun N-terminal kinase (JNK) signaling cascade. ASK1 has been implicated in cytokine- and stress-induced apoptosis. However, little is known about the role of ASK1 in apoptosis in hydrogen peroxide (H2O2)-stimulated pulmonary vascular endothelial cells and how ASK1-mediated apoptosis is executed. To clarify this issue, we examined the role of ASK1-p38 MAPK/JNK cascade in apoptosis and caspase-3 activation in H2O2-stimulated pulmonary vascular endothelial cells.

Design: Experimental laboratory study.

Setting: University laboratory.

Subjects: Normal human pulmonary artery endothelial cells.

Interventions: Western blot analysis and quantification of apoptosis in cells.

Measurements And Main Results: The results showed that H2O2 induced ASK1 phosphorylation and concomitantly p38 MAPK and JNK phosphorylation as well as induced caspase-3 activation in pulmonary vascular endothelial cells. To further characterize the role of ASK1 cascade in H2O2-induced apoptosis of pulmonary vascular endothelial cells, the dominant negative form of ASK1-stably transfected porcine artery endothelial cells was used. p38 MAPK and JNK phosphorylation, caspase-3 activation, and apoptosis in the dominant negative form of ASK1-stably transfected porcine artery endothelial cells were depressed compared with those in the parental porcine artery endothelial cells.

Conclusion: ASK1-p38 MAPK/JNK cascade regulates apoptosis of H2O2-stimulated human pulmonary vascular endothelial cells.