In vivo alterations of IFN regulatory factor-1 and PIAS1 protein levels in cystic fibrosis epithelium
Thomas J. Kelley, Heather L. Elmer
Thomas J. Kelley, Heather L. Elmer
View: Text | PDF
Article

In vivo alterations of IFN regulatory factor-1 and PIAS1 protein levels in cystic fibrosis epithelium

Abstract

Inducible nitric oxide synthase-2 (NOS2) expression has been shown to be reduced in cystic fibrosis (CF) epithelial cells. Reduced NOS2 expression is unexpected, given the inflammatory nature of CF airway disease, and is an indication that cell-signaling mechanisms necessary for proper NOS2 regulation are probably altered in CF epithelium. Therefore, we examined the expression levels of regulatory factors necessary for NOS2 expression in CF epithelium and showed that IFN regulatory factor-1 (IRF-1) is necessary for full NOS2 expression. Mice lacking IRF-1 expression have diminished epithelial NOS2 expression, as well as reduced NO-dependent chloride transport across the nasal epithelia. Furthermore, IRF-1 protein expression is reduced in nasal and intestinal epithelial cells from CF mice, suggesting a possible mechanism for the CF-related reduction of epithelial NOS2 expression. Active signal transducer and activator of transcription-1 (Stat1) is necessary for both NOS2 and IRF-1 expression. We found that protein levels of Stat1 were increased in CF cells, but that the active phosphorylated form of Stat1 was bound to the protein inhibitor of activated Stat1 (PIAS1). We propose that increased levels of PIAS1 diminish certain cell-signaling pathways, resulting in reduced IRF-1 and NOS2 expression in CF epithelial cells.

Authors

Thomas J. Kelley, Heather L. Elmer

×

Figure 8

Options: View larger image (or click on image) Download as PowerPoint
Stat1-mediated cell signaling in 9/HTEo– pCEP2 and pCEPRF cells. Cells w...
Stat1-mediated cell signaling in 9/HTEo– pCEP2 and pCEPRF cells. Cells were cotransfected with pGAS-Luc and pEGFPN1 and stimulated with either 10, 25, or 100 units/mL IFN-γ or with 10% serum as described. Data were normalized for transfection efficiency as measured by GFP expression, and are presented as a ratio of relative light units (RLU) to relative fluorescence units (RFU). The number of experiments (n) is shown in parentheses above each bar. Error bars represent SEM. AP < 0.001; BP < 0.0001, pCEP2 vs. pCEPRF cells under each experimental condition, by Student’s t test. C,DSignificant stimulation of luciferase activity in pCEP2 cells compared with untreated (NT) pCEP2 cells as measured by Duncan’s multiple range test (CP < 0.01; DP < 0.0001). E,FSignificant stimulation of luciferase activity in pCEPRF cells compared with untreated (NT) pCEPRF cells, as measured by Duncan’s multiple range test (EP < 0.01; FP < 0.0001).