Strain-dependent difference in inducible nitric oxide synthesis (iNOS) expression in rat pancreatic islets correlates with interferon regulating factor 1 (IRF-1) and heat shock protein 70 (HSP70) expression.
Nitric oxide (NO) may be a necessary but not sufficient mediator of cytokine-mediated, selective beta-cell destruction. Previously, we have described a difference in NO-dependent IL-1beta sensitivity in vivo and in vitro of pancreatic islets from two rat strains, Brown Norway (BN) and Wistar Kyoto (WK), the latter being the more sensitive strain. Here we investigated whether strain-dependent, differential islet iNOS expression was associated with differences in islet expression of the IL-1 receptor type 1(IL-1RI) or interferon regulating factor 1 (IRF-1), and/or caused differences in HSP70 expression, a marker of cell defence against oxidative stress.


METHODS
isolated islets from both rat strains were exposed to increasing concentrations of IL-1beta (0-150 pg/ml) for 24 hours or for varying culture periods (4-48 hours) to 15 pg/ml of IL-1beta.


METHODS
accumulated insulin and nitrite release into incubation medium, and islet mRNA and protein expression of iNOS, IL-1RI, IRF-1 and HSP70 by semi-quantitative RT-PCR and Western blotting.


RESULTS
Higher insulin and lower nitrite release into the incubation medium were seen for BN compared to WK rats islets in both dose- and time-response experiments. IRF-1 expression preceded iNOS expression and was more pronounced in WK than in BN islets. No strain differences were observed for islet expression of IL-1RI. A strain-dependent HSP70 expression in response to IL-1beta with the highest levels in WK rat islets following iNOS expression was seen.


CONCLUSIONS
There was a strain-dependent difference in iNOS expression which was associated with IRF-1 and HSP70 expression.
Johannesen
J
J
Steno Diabetes Center, Niels Steensensvej 2, DK-2820 Gentofte, Denmark.
Pociot
F
F
Karlsen
A E
AE
Mandrup-Poulsen
T
T
Nerup
J
J
D000818:Animals; D004268:DNA-Binding Proteins / Q000187:drug effects / Q000235:genetics*; D004305:Dose-Response Relationship, Drug; D020869:Gene Expression Profiling; D018840:HSP70 Heat-Shock Proteins / Q000819:agonists / Q000235:genetics / Q000378:metabolism; D066298:In Vitro Techniques; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D050856:Interferon Regulatory Factor-1; D007375:Interleukin-1 / Q000378:metabolism* / Q000494:pharmacology; D007515:Islets of Langerhans / Q000166:cytology / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D009573:Nitrites / Q000378:metabolism; D010750:Phosphoproteins / Q000187:drug effects / Q000235:genetics*; D015800:Protozoan Proteins / Q000819:agonists / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis* / Q000187:drug effects; D051381:Rats; D017208:Rats, Wistar; D017472:Receptors, Interleukin-1 / Q000187:drug effects / Q000235:genetics*; D013045:Species Specificity
D004268:DNA-Binding Proteins; D018840:HSP70 Heat-Shock Proteins; C490435:Hspa2 protein, rat; D007328:Insulin; D050856:Interferon Regulatory Factor-1; D007375:Interleukin-1; C494259:Irf1 protein, rat; D009573:Nitrites; D010750:Phosphoproteins; D015800:Protozoan Proteins; D012333:RNA, Messenger; D017472:Receptors, Interleukin-1; C081884:heat-shock protein 70.1; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496318:Nos2 protein, rat