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Cytokine receptors activate multiple signal transduction pathways, resulting in the induction of specific target genes. We have recently identified a hematopoietic cell-specific immediate-early gene, DUB-1, that encodes a growth-regulatory deubiquitinating enzyme. The DUB-1 gene contains a 112-bp enhancer element that is specifically induced by the beta c subunit of the interleukin-3 (IL-3) receptor. To investigate the mechanism of DUB-1 induction, we examined the effects of dominant-negative forms of JAK kinases, STAT transcription factors, and Raf-1 in transient transfection assays. In Ba/F3 cells, IL-3 induced a dose-dependent activation of DUB-1-luciferase (luc) and GAS-luc reporter constructs. A dominant-negative form of JAK2 (truncated at amino acid 829) inhibited the induction of DUB-1-luc and GAS-luc by IL-3. A dominant-negative form of STAT5 (truncated at amino acid 650) inhibited the induction of GAS-luc but not DUB-1-luc. A dominant-negative form of Raf-1 inhibited the induction of DUB-1-luc but had no effect on the induction of GAS-luc by IL-3. The requirement for JAK2 in the stimulation of the DUB-1 enhancer was further supported by the suppression of DUB-1 induction in Ba/F3 cells stably expressing the dominant-negative JAK2 polypeptide. We hypothesize that IL-3 activates a JAK2/Raf-1 signaling pathway that is required for DUB-1 induction and is independent of STAT5.

Type

Journal article

Publication Date

1997

Volume

17

Pages

3364 - 3372

Keywords

Animal Cell Division Cells, Cultured DNA/metabolism DNA-Binding Proteins/metabolism Enhancer Elements (Genetics) *Gene Expression Regulation, Enzymologic Growth Inhibitors/biosynthesis/*genetics Immediate-Early Proteins/biosynthesis/*genetics Interferon-alpha/metabolism Interleukin-3/metabolism Mice Protein-Serine-Threonine Kinases/metabolism Protein-Tyrosine Kinase/genetics/*metabolism Proto-Oncogene Proteins/metabolism Receptors, Interleukin-3/metabolism Signal Transduction Support, Non-U.S. Gov't Support, U.S. Gov't, P.H.S. Trans-Activators/metabolism Transfection