Ceramide-induced enhancement of secretory phospholipase A2 expression via generation of reactive oxygen species in tumor necrosis factor-alpha-stimulated mesangial cells.
Since prostanoids such as prostaglandin E2 play a pivotal role in modulating renal function, we investigated the involvement of ceramide in expression of secretory phospholipase A2 (sPLA2) and cyclooxygenase-2 (COX-2) in tumor necrosis factor-alpha (TNF-alpha)-stimulated mesangial cells. TNF-alpha stimulation increased ceramide generation in parallel with a decrease in sphingomyelin. Pretreatment with exogenous sphingomyelinase (SMase) dose-dependently enhanced TNF-alpha-stimulated increases in COX-2 protein and sPLA) activity. SMase also augmented TNF-alpha-mediated nuclear factor kappaB (NF-kappaB) activation. N-acetylcysteine (NAC), an antioxidant, completely inhibited the SMase-induced increase in sPLA2 activity, whereas NAC inhibited partially the activity stimulated with TNF-alpha alone. Under the conditions, NAC completely inhibited reactive oxygen species (ROS) production induced by SMase followed by TNF-alpha. These results suggest that ceramide elicits up-regulation of NF-kappaB through ROS production, which, in turn, leads to stimulation of COX-2 and sPLA2 expression. Therefore, ceramide may be implicated in the pathogenesis of renal abnormalities.
Kitatani
Kazuyuki
K
Department of Pathological Biochemistry, Kyoto Pharmaceutical University, Misasagi, Yamashina, Kyoto 607-8414, Japan.
Akiba
Satoshi
S
Sato
Takashi
T
D000111:Acetylcysteine / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D002518:Ceramides / Q000494:pharmacology*; D051546:Cyclooxygenase 2; D005920:Glomerular Mesangium / Q000187:drug effects / Q000201:enzymology*; D016328:NF-kappa B / Q000378:metabolism; D010741:Phospholipases A / Q000096:biosynthesis*; D054467:Phospholipases A2; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013108:Sphingomyelin Phosphodiesterase / Q000378:metabolism; D013109:Sphingomyelins / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D002518:Ceramides; D016328:NF-kappa B; D017382:Reactive Oxygen Species; D013109:Sphingomyelins; D014409:Tumor Necrosis Factor-alpha; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases; D010741:Phospholipases A; D054467:Phospholipases A2; D013108:Sphingomyelin Phosphodiesterase; D000111:Acetylcysteine