Protein kinase Cdelta activation by interleukin-1beta stabilizes inducible nitric-oxide synthase mRNA in pancreatic beta-cells.
Exposure of pancreatic islets to cytokines such as interleukin (IL)-1beta induces a variety of proinflammatory genes including type II nitric-oxide synthase (iNOS) which produces nitric oxide (NO). NO is thought to be a major cause of islet beta-cell dysfunction and apoptotic beta-cell death, which results in type I diabetes. Since protein kinase C (PKC) mediates some of the actions of cytokines in other cell types, our aim was to assess the role of PKC in IL-1beta-induced iNOS expression in pancreatic beta-cells. PKCdelta, but not PKCalpha, was specifically activated in the rat INS-1 beta-cell line by IL-1beta as assessed by membrane translocation. Moreover, iNOS expression and NO production were significantly attenuated by the PKCdelta specific inhibitor rottlerin and overexpression of a PKCdelta kinase-dead mutant protein. Conversely, overexpression of PKCdelta wild type protein significantly potentiated this response. These results were confirmed at the mRNA level by reverse transcriptase-polymerase chain reaction. However, a role at the level of transcriptional regulation appeared unlikely, since PKCdelta was not required for the activation of NF-kappaB, activating protein 1, and activating transcription factor 2 signaling pathways in response to IL-1beta. There was, however, a significant increase in iNOS mRNA stability mediated by PKCdelta wild type, while PKCdelta kinase-dead acted reciprocally, reducing iNOS mRNA stability. The results indicate that, in addition to transcriptional activation, mRNA stabilization is a key component of the mechanism by which IL-1beta stimulates iNOS expression in beta-cells and that PKCdelta plays an essential role in this process. PKCdelta activation may therefore have significant consequences with regard to cellular function and viability when beta-cells are exposed to IL-1beta and potentially other cytokines.
Carpenter
L
L
Garvan Institute of Medical Research, St. Vincents Hospital, 384 Victoria St, Darlinghurst, Sydney, 2010, Australia.
Cordery
D
D
Biden
T J
TJ
D000818:Animals; D002460:Cell Line; D002478:Cells, Cultured; D004789:Enzyme Activation; D007375:Interleukin-1 / Q000494:pharmacology*; D007515:Islets of Langerhans / Q000187:drug effects / Q000201:enzymology*; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D020935:MAP Kinase Signaling System; D008297:Male; D009154:Mutation; D009569:Nitric Oxide / Q000096:biosynthesis; D019001:Nitric Oxide Synthase / Q000096:biosynthesis / Q000235:genetics*; D052247:Nitric Oxide Synthase Type II; D011493:Protein Kinase C / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D051745:Protein Kinase C-delta; D021381:Protein Transport; D020871:RNA Stability; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar
D007375:Interleukin-1; D007527:Isoenzymes; D012333:RNA, Messenger; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; C497260:Prkcd protein, rat; D011493:Protein Kinase C; D051745:Protein Kinase C-delta