IL-1 beta induces serine protease inhibitor 3 (SPI-3) gene expression in rat pancreatic beta-cells. Detection by differential display of messenger RNA

Immune-mediated beta-cell damage induces diverse intracellular signals, lea ding to transcription of different genes which may either contribute to bet a-cell repair and/or defence or lead to cell death. The cytokine interleuki n-l beta (IL-1) is a potential mediator of beta-cell dysfunction and damage in type 1 diabetes mellitus, To understand the molecular actions of this c ytokine upon beta-cells, this study aimed at the cloning of genes induced i n FAGS-purified rat pancreatic beta-cells by a 6- or 24-h exposure to IL-1 by using differential display of mRNA with reverse transcription-polymerase chain reaction (DDRT-PCR), Among these cytokine-induced genes, a gene enco ding for rat serine protease inhibitor (SPI-3) was isolated, SPI-3 may be i nvolved in cellular defence responses against inflammatory stress, RT-PCR a nalysis confirmed that SPI-3 mRNA expression in rat beta-cells is increased by IL-l at an early stage (2 h), with maximal accumulation during 6-12 h a nd decline after 24 h, Similar observations were made in mouse pancreatic i slets and in the rat insulinoma cell line RINm5F, IFN-gamma neither increas ed SPI-3 gene expression nor potentiated its induction by IL-1 in rat beta- cells, The stimulatory effects of IL-1 on SPI-3 mRNA expression were decrea sed by co-incubation with an inhibitor of gene transcription (actinomycin D ), an inhibitor of protein synthesis (cycloheximide) or an inhibitor of NF- kappa B activation (PDTC), On the other hand, a blocker of inducible nitric oxide synthase (iNOS) activity (N-G-methyl-L-arginine) did not prevent IL- 1-induced SPI-3 expression, Thus, SPI-3 mRNA expression following IL-1 expo sure depends on gene transcription, protein synthesis and activation of the nuclear transcription factor NF-kappa B, but it is independent of NO forma tion, (C) 1999 Academic Press.