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Interleukin‐1β inhibits ATP‐induced protein kinase B activation in renal mesangial cells by two different mechanisms: the involvement of nitric oxide and ceramide
Author(s) -
Rölz Waltraud,
Xin Cuiyan,
Ren Shuyu,
Pfeilschifter Josef,
Huwiler Andrea
Publication year - 2003
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1038/sj.bjp.0705064
Subject(s) - protein kinase b , nitric oxide synthase , mesangial cell , nitric oxide , phosphatase , ceramide , chemistry , kinase , phosphorylation , protein kinase a , microbiology and biotechnology , biochemistry , endocrinology , medicine , biology , apoptosis , in vitro
Extracellular nucleotides, like ATP and UTP, have been shown to activate the protein kinase B (PKB) pathway in mesangial cells. In this study we report that the pro‐inflammatory cytokine interleukin‐1β (IL‐1β) inhibits ATP‐induced PKB activation. Pretreatment of mesangial cells with IL‐1β leads to a time‐dependent decrease of ATP‐induced PKB phosphorylation. Maximal inhibition is seen after 6 h of pretreatment. Incubating cells with IL‐1β in the presence of the NO synthase inhibitor, N ‐monomethyl‐ L ‐arginine ( L ‐NMMA), reversed the IL‐1β inhibition of PKB activity. A similar decrease in ATP‐evoked PKB activation is obtained when cells were pretreated with the nitric oxide (NO) donor, ( Z )‐1‐[2‐Aminoethyl)‐ N ‐(2‐ammonioethyl)amino]diazen‐1‐ium‐1,2‐diolate (Deta‐NO), but not with the cell‐permeable cGMP analogue, 8‐bromo‐cGMP. The NO‐ and IL‐1β‐mediated delayed inhibition of PKB activity is completely reversed by the phosphatase inhibitor calyculin A, but not by ocadaic acid, suggesting that NO upregulates a protein phosphatase activity, which most probably belongs to the group of protein phosphatases type 1. In addition, IL‐1β also triggers a short‐term and transient inhibitory effect on ATP‐induced PKB activation which is maximal after 2–5 min of pre‐incubation with IL‐1β. This effect occurs independently of NO generation, because no NO synthase is expressed at that time, and consequently, L ‐NMMA does not reverse the effect. Rather an involvement of the sphingolipid ceramide is likely, since IL‐1β triggers rapid ceramide formation and incubation of cells with the cell‐permeable C6‐ceramide blocked ATP‐induced PKB phosphorylation. In summary, our data show that IL‐1β exerts both short‐term and long‐term inhibitory effects on ATP‐stimulated PKB activation, the short‐term effect probably involves ceramide formation, whereas the long‐term effect is due to inducible NO synthase induction and subsequent NO formation. These results reveal a further facet in the mechanisms of ceramide‐ and NO‐induced cell death, i.e. by turning off the survival signal elicited by PKB.British Journal of Pharmacology (2003) 138 , 461–468. doi: 10.1038/sj.bjp.0705064