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. Author manuscript; available in PMC: 2009 Jul 1.
Published in final edited form as: J Immunol. 2008 Jul 1;181(1):449–463. doi: 10.4049/jimmunol.181.1.449

FIGURE 5.

FIGURE 5

Down-regulation of FcRn expression by IFN-γ is dependent on JAK1 and STAT-1 expression. A–C, Wild-type (WT) 2fTGH (A), STAT-1-null U3A (B), and JAK1-null U4A (C) cells were transiently transfected with phFcRnLuc or pM2 construct. D, STAT-1-null U3A or JAK1-null U4A cells were transiently transfected by phFcRnLuc along with pSTAT-1 or pJAK1 constructs. E, The 2fTGH cells were transiently transfected with phFcRnLuc together with vector backbone or pFLAG-PIAS1. Twenty-four hours after transfection, all groups of cells were either mock-treated or treated with IFN-γ for 24 h. Cells were then harvested and protein extracts were prepared for the luciferase assay. Transcriptional activity was measured as firefly luciferase activity and normalized to Renilla luciferase activity. The results show the mean value from three independent experiments. *, p < 0.05. F, Interaction of PIAS1 and STAT-1 proteins. Cell lysates from mock- (lane 1) or IFN-γ-treated (lane 2) 2fTGH cells were immunoprecipitated (IP) with anti-FLAG mAb, and immunoprecipitates were subjected to electrophoresis on a 12% SDS-polyacrylamide gel under reducing conditions and transferred to a nitrocellulose membrane for Western blotting with anti-STAT-1 Ab. Immunoblots were developed with ECL. Experiment was at least performed two times. The cell lysates (bottom row) were blotted to monitor the expression of PIAS1. HC, Heavy chain.