Tyrosine kinase involvement in IL-1 beta-induced expression of iNOS by beta-cells purified from islets of Langerhans.
Nitric oxide is believed to mediate the inhibitory effects of cytokines on glucose-stimulated insulin secretion by both rat and human islets. The aims of this study were 1) to determine the cellular source of the cytokine-inducible isoform of nitric oxide synthase (iNOS) expressed in islets following cytokine stimulation and 2) to determine whether tyrosine kinase activity participates in cytokine-induced iNOS expression. In this report we demonstrate that the cytokine interleukin-1 beta (IL-1 beta) stimulates the expression of iNOS and the formation of nitric oxide (as determined by nitrite formation, a stable oxidative product of nitric oxide) by isolated intact rat islets and by primary beta-cells purified by fluorescence-activated cell sorting (FACS). Both the expression of iNOS and nitrite formation induced by IL-1 beta were prevented by the mRNA transcriptional inhibitor actinomycin D. IL-1 beta did not induce the expression of iNOS by FACS-purified alpha-cells, the other major endocrine cell type of the islet. The tyrosine kinase inhibitors genistein and herbimycin A prevented IL-1 beta-induced expression of immunoprecipitable iNOS and nitrite release by islets, by insulinoma RINm5F cells, and by FACS-purified beta-cells. Herbimycin A and genistein also prevented IL-1 beta-induced iNOS mRNA accumulation as determined by Northern blot analysis of total RNA isolated from RINm5F cells. These findings indicate tyrosine kinase activation participates in IL-1 beta-induced expression of iNOS by the insulin-secreting beta-cell.(ABSTRACT TRUNCATED AT 250 WORDS)
Corbett
J A
JA
Department of Pathology, Washington University School of Medicine, St. Louis 63110.
Kwon
G
G
Misko
T P
TP
Rodi
C P
CP
McDaniel
M L
ML
D000594:Amino Acid Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D004790:Enzyme Induction; D007375:Interleukin-1 / Q000494:pharmacology*; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism*; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D008297:Male; D019001:Nitric Oxide Synthase; D011233:Precipitin Tests; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
D007375:Interleukin-1; D007527:Isoenzymes; D012333:RNA, Messenger; D019001:Nitric Oxide Synthase; D000594:Amino Acid Oxidoreductases; D011505:Protein-Tyrosine Kinases