Nitric oxide stimulates the stress-activated protein kinase p38 in rat renal mesangial cells

Nitric oxide (NO) has gained increased attention as a diffusible universal messenger that plays a crucial role in the pathogenesis of inflammatory and autoimmune diseases. Recently, we reported that exogenous NO is able to ac tivate the stress-activated protein kinase (SAPK) cascade in mesangial cell s, Here, we demonstrate that exposure of glomerular mesangial cells to comp ounds releasing NO, including spermine-NO and (N-methyl-N-[ 6-(N-methylammo niohexyl)amino]diazen)-1-ium-1,2-diolate (MAHMA-NO), results in an activati on of the stress-activated p38-mitogen-activated protein kinase (p38-MAPK) cascade as measured by the phosphorylation of the activator of transcriptio n factor-2 (ATF(2)) in an immunocomplex kinase assay. Activation of the p38 -MAPK cascade by a short stimulation (10 min) with the NO donor MAHMA-NO ca uses a large increase in ATF2 phosphorylation that is several times greater than that observed after stimulation with interleukin-1 beta, a well-known activator of the p38-MAPK pathway, Time course studies reveal that MAHMA-N O causes rapid and maximal activation of p38-MAPK after 10 min of stimulati on and that activation declines to basal levels within 60 min. The longer-l ived NO donor spermine-NO causes a comparable rapid activation of the p38-M APK pathway; however, the increased activation state of p38-MAPK was mainta ined for several hours before control values were reattained after 24 h of stimulation. Furthermore, the NO donors also activated the classical extrac ellular signal-regulated kinase (ERK) p44-MAPK cascade as shown by phosphor ylation of the specific substrate cytosolic phospholipase A(2) in an immuno complex kinase reaction. Both MAHMA-NO and spermine-NO cause a rapid activa tion of p44-MAPK after 10min of stimulation. Interestingly, there is a seco nd delayed peak of p44-MAPK activation after 4-24h of stimulation with NO d onors. These results suggest that there is a differential activation pattern for s tress-activated and mitogen-activated protein kinases by NO and that the in tegration of these signals may lead to specific cell responses.