Mitogen-activated protein kinases (MAPKs) belong to the group of serine-threonine kinases that are rapidly activated in response to growth factor stimulation. In adult mammalian cells, the MAPK family includes extracellular signal-regulated kinases 1 and 2 (ERK1 and ERK2 or p44mapk and p42mapk), which translocate to the nucleus and integrate signals from second messengers leading to cellular proliferation or differentiation, but the specific role of MAPKs in neonatal pulmonary vascular smooth muscle is not well understood. Expression of p44mapk and p42mapk in primary cultured pulmonary vascular smooth muscle cells from neonatal (1-2 day old) rats was identified by Western immunoblot analysis and treatment with 10 nM endothelin-1 (ET-1), a potent vasoconstrictor with vascular mitogenic properties, induced cell proliferation, and phosphorylation of both p44 mapk and p42mapk. The protein kinase C (PKC) isozyme inhibitor (α, β, γ, δ, ζ) Go 6983, the ET A receptor antagonist BQ 123, and the MAPK kinase inhibitor PD98059 blocked the cell proliferation response to ET-1. Also, BQ 123, Go 6983, and PKC inhibitor 20-28 (Myr-N-FARKGAL-RQ-NH2-PKCα antagonist) inhibited ET-1-induced phosphorylation of both p44mapk and p42 mapk. In contrast, the reactive oxygen species (ROS) inhibitor diphenylene iodonium (DPI), the PKCδ inhibitor rottlerin, and the ET B receptor antagonist BQ 788 did not block ET-1-induced phosphorylation of MAPKs. Collectively, these data demonstrate the expression and phosphorylation of MAPKs by ET-1 and suggests that MAPK activation and cell proliferation by ET-1 occurs via ETA receptor stimulation and specific PKC isozyme activation in rat neonatal pulmonary vascular smooth muscle.
- Mitogen-activated protein kinase
- PKC isozymes
- Pulmonary vascular smooth muscle
ASJC Scopus subject areas
- Pulmonary and Respiratory Medicine