Interleukin-1beta-induced rat pancreatic islet nitric oxide synthesis requires both the p38 and extracellular signal-regulated kinase 1/2 mitogen-activated protein kinases.
Interleukin-1beta (IL-1beta) is cytotoxic to rat pancreatic beta-cells by inhibiting glucose oxidation, causing DNA damage and inducing apoptosis. Nitric oxide (NO) is a necessary but not sufficient mediator of these effects. IL-1beta induced kinase activity toward Elk-1, activation transcription factor 2, c-Jun, and heat shock protein 25 in rat islets. By Western blotting with phosphospecific antibodies and by immunocomplex kinase assay, IL-1beta was shown to activate extracellular signal-regulated kinase (ERK) 1/2 and p38 mitogen-activated protein kinase (p38) in islets and rat insulinoma cells. Specific ERK1/2 and p38 inhibitors individually reduced but in combination blocked IL-1beta-mediated islet NO synthesis, and reverse transcription-polymerase chain reaction of inducible NO synthase mRNA showed that ERK1/2 and p38 controlled IL-1beta-induced islet inducible NO synthase expression at the transcriptional level. Hyperosmolarity caused phosphorylation of Elk-1, activation transcription factor 2, and heat shock protein 25 and activation of ERK1/2 and p38 in islets comparable to that induced by IL-1beta but did not lead to NO synthesis. Inhibition of p38 but not of ERK1/2 attenuated IL-1beta-mediated inhibition of glucose-stimulated insulin release. We conclude that ERK1/2 and p38 activation is necessary but not sufficient for IL-1beta-mediated beta-cell NO synthesis and that p38 is involved in signaling of NO-independent effects of IL-1beta in beta-cells.
Larsen
C M
CM
Steno Diabetes Center, 2820 Gentofte, Denmark.
Wadt
K A
KA
Juhl
L F
LF
Andersen
H U
HU
Karlsen
A E
AE
Su
M S
MS
Seedorf
K
K
Shapiro
L
L
Dinarello
C A
CA
Mandrup-Poulsen
T
T
D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000502:physiology*; D004789:Enzyme Activation / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D005947:Glucose / Q000378:metabolism; D007328:Insulin / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology*; D007515:Islets of Langerhans / Q000201:enzymology*; D020928:Mitogen-Activated Protein Kinases; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D009994:Osmolar Concentration; D010179:Pancreas / Q000187:drug effects*; D010766:Phosphorylation; D012333:RNA, Messenger / Q000187:drug effects; D051381:Rats; D011919:Rats, Inbred Strains; D015398:Signal Transduction / Q000502:physiology; D014407:Tumor Cells, Cultured; D048051:p38 Mitogen-Activated Protein Kinases
D007328:Insulin; D007375:Interleukin-1; D012333:RNA, Messenger; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D005947:Glucose