Discovery of Gene Networks Regulating Cytokine-Induced Dysfunction and Apoptosis in Insulin-Producing INS-1 Cells

  1. Burak Kutlu1,
  2. Alessandra K. Cardozo1,
  3. Martine I. Darville1,
  4. Mogens Kruhøffer2,
  5. Nils Magnusson2,
  6. Torben Ørntoft2 and
  7. Décio L. Eizirik1
  1. 1Laboratory of Experimental Medicine, Université Libre de Bruxelles, Brussels, Belgium
  2. 2Molecular Diagnostic Laboratory, Department of Clinical Biochemistry, Aarhus University Hospital, Skejby, Denmark
  1. Address correspondence reprint requests to Décio L. Eizirik, Laboratory of Experimental Medicine CP 618, Université Libre de Bruxelles, Route de Lennik, 808, B-1070, Brussels, Belgium. E-mail: deizirik{at}ulb.ac.be

Abstract

Locally released cytokines contribute to β-cell dysfunction and apoptosis in type 1 diabetes. In vitro exposure of insulin-producing INS-1E cells to the cytokines interleukin (IL)-1β + interferon (IFN)-γ leads to a significant increase in apoptosis. To characterize the genetic networks implicated in β-cell dysfunction and apoptosis and its dependence on nitric oxide (NO) production, we performed a time-course microarray analysis of cytokine-induced genes in insulin-producing INS-1E cells. INS-1E cells were exposed in duplicate to IL-1β + IFN-γ for six different time points (1, 2, 4, 8, 12, and 24 h) with or without the inducible NO synthase (iNOS) blocker NG-monomethyl-l-arginine (NMA). The microarray analysis identified 698 genes as cytokine modified (≥2.5-fold change compared with control) in at least one time point. Based on their temporal pattern of variation, the cytokine-regulated genes were classified into 15 clusters by the k-means method. These genes were further classified into 14 different groups according to their putative function. Changes in the expression of genes related to metabolism, signal transduction, and transcription factors at all time points studied indicate β-cell attempts to adapt to the effects of continuous cytokine exposure. Notably, several apoptosis-related genes were modified at early time points (2–4 h) preceding iNOS expression. On the other hand, 46% of the genes modified by cytokines after 8–24 h were NO dependent, indicating the important role of this radical for the late effects of cytokines. The present results increase by more than twofold the number of known cytokine-modified genes in insulin-producing cells and yield comprehensive information on the role of NO for these modifications in gene expression. These data provide novel and detailed insights into the gene networks activated in β-cells facing a prolonged immune assault.

Footnotes

  • Additional information on this article can be found in two online data supplements at http://diabetes.diabetesjournals.org.

    • Accepted August 19, 2003.
    • Received May 15, 2003.
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