Suppressor of Cytokine Signaling -3 inhibits cytokine-mediated mitogen-activated protein kinase/nuclear factor-[kappa]B activation, nitrogen oxide production, and apoptosis in rat pancreatic [beta]-cells

The cytokines interleukin (IL)-I and interferon (IFN)-[gamma] are believed to be mediators of immune-mediated [beta]-cell destruction in type 1 diabetes. Inhibition of the nuclear factor (NF)-[kappa]B and mitogen-activated protein kinase (MAPK) pathways protects [beta]-cells against cytokine-induced apoptosis, partly because of inhibition of inducible nitric oxide synthase expression and nitric oxide (NO) generation. We have previously shown that suppressor of cytokine signaling (SOCS)-3 prevents cytokine-induced NO production and apoptosis in a [beta]-cell line. The aim of this study was to investigate by microarray the gene pattern induced by IL-1 and its suppression by SOCS-3 in a [beta]-cell line. Furthermore, we also investigated whether SOCS-3 inhibits the NF-[kappa]B and MAPK pathways, NO production, and apoptosis induction in primary rat [beta]-cells. By microarray analysis (Affymetrix U34A Array), we found that IL-1 stimulation (150 pg/ml, 6 h) upregulated 23 annotated genes, 15 of which were inhibited by SOCS-3. Interestingly, of these 15 genes, 9 have previously been reported to be NF-[kappa]B dependent. Using an adenovirus expression approach, we found by Western blotting that SOCS-3 inhibited I[kappa]B degradation and MAPK activation in dispersed rat islets cultures exposed to IL-1 (250 pg/ml, 15 min). In addition, both NO production and apoptosis induction by IL-1 + IFN-[gamma] (250 and 10 ng/ml, 24 h) were suppressed 50% by SOCS-3. In conclusion, we show that expression of SOCS-3 inhibits NF-[kappa]B-dependent gene transcription in a [beta]-cell line and inhibits I[kappa]B degradation and MAPK activation in primary rat [beta]-cells. These findings elucidate the signaling pathways involved in the mechanism by which SOCS-3 reduces cytokine-induced toxicity in [beta]-cells.