Abstract

Objective: Cytokines contribute to pancreatic β-cell death in T1D. This effect is mediated by complex gene networks that remain to be characterized. We presently utilized array analysis to define the global expression pattern of genes, including spliced variants, modified by the cytokines IL-1β+IFN-γ and TNF-α+IFN-γ in primary rat β-cells.

Research Design and Methods: FACS-purified rat β-cells were exposed to IL-1β+IFN-γ or TNF-α+IFN-γ for 6 or 24 h and global gene expression was analyzed by microarray. Key results were confirmed by RT-PCR, and siRNAs were used to investigate the mechanistic role of novel and relevant transcription factors identified by pathway analysis.

Results: Nearly 16.000 transcripts were detected as present in β-cells, with temporal differences in the number of genes modulated by IL-1β+IFNγ or TNF-α+IFN-γ. These cytokine combinations induced differential expression of inflammatory response genes, which is related to differential induction of IRF-7. Both treatments decreased the expression of genes involved in the maintenance of β-cell phenotype and growth/regeneration. Cytokines induced HIF-1α, which in this context has a pro-apoptotic role. Cytokines also modified the expression of >20 genes involved in RNA splicing, and exon array analysis showed cytokine-induced changes in alternative splicing of more than 50% of the cytokine-modified genes.

Conclusion: The present study doubles the number of known genes expressed in primary β-cells, modified or not by cytokines, and indicates the biological role for several novel cytokine-modified pathways in β-cells. It also shows that cytokines modify alternative splicing in β-cells, opening a new avenue of research for the field.