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. 2022 Jul 4;12(11):5086–5102. doi: 10.7150/thno.74989

Figure 5.

Figure 5

UBR5 is crucial for IFN-γ-induced activation of STAT1 and IRF1 transcription. (A-B) The mRNA (A) and protein (B) levels of UBR5, STAT1, pSTAT1 and IRF1 were detected in WT, Ubr5-/- and hUBR5-reconstituted Ubr5-/- 4T1 cells with or without IFN-γ stimulation. (C-D) The mRNA (C) and protein levels (D) of STAT1 and IRF1were detected in IFN-γ-treated UBR5-knockdown BT549 (C and D) and MDA-MB-231 (D) stable cell lines. (E-G) BT549, MDA-MB-231 and MCF7 cells were transfected with either an empty vector or UBR5 plasmids. 24 hours later, the cells were treated with IFN-γ for 24 h. Then the mRNA and protein levels of STAT1 (E and G) and IRF1 (F and G) were measured by qPCR and western blot, respectively. (H) Surface PD-L1 levels were detected in IFN-γ-treated GFP, Ubr5-/- 4T1 cells and GFP 4T1 cells treated with siNC, siSTAT1 or siIRF1. GAPDH was used for normalization. (I) Luciferase reporter vectors containing either STAT1 or IRF1 promoter regions were cotransfected with an empty vector or UBR5 plasmids into the indicated cells. After 24 h, the transfected cells were treated with IFN-γ stimulation for 24 h, the cells were lysed to perform luciferase assay. The results are presented as the mean ± SEM from three individual experiments. *P < 0.05, **P < 0.01, ***P< 0.001, ****P < 0.0001. (J) The IRF1 and STAT1 binding sites in the mPdl1 promoter region were predicted using the ALGGEN website. (K) Summary of the results of a ChIP assay using anti-IRF1, STAT1, H3K4me1 and H3K27ac antibodies in WT, Ubr5-/- or hUBR5-reconstituted Ubr5-/- 4T1 cells after treatment with or without IFN-γ.