FIG 12.
KDM2B prolongs the half-life of c-Jun protein, which requires KDM2B’s F-box domain. (A to C) Effect of KDM2B-OE on the mRNA and protein expression of AP-1 subunits. SLK cells were first transduced with lenti-GFP or lenti-3×FLAG-KDM2B for 72 h, followed by treatment with DMSO or 20 nM TPA. Seventy-two hours posttreatment, RT-qPCR and immunoblotting were performed. (A) Gene expression of c-Fos and c-Jun measured by RT-qPCR. t test was performed between GFP-OE and KDM2B-OE samples, and P < 0.05 (*) was considered statistically significant. (B) Immunoblot analysis of c-Jun expression. Tubulin was used as a loading control. (C) Quantification of c-Jun bands in panel B. c-Jun level was normalized by tubulin expression. (D) Effect of KDM2B on the half-life of c-Jun. HEK293T cells were transfected with empty vector or 3×FLAG-KDM2B WT, ΔF-box, or F-box–LRR mutant for 48 h, which was followed by treatment of the cells with 0.5 mg/ml CHX for the indicated length of time. Immunoblotting was performed for c-Jun, KDM2B, and tubulin at the indicated time points. (E) Quantification of c-Jun level by normalizing with tubulin expression. (F) Working model for illustrating the mechanism of how SCFKDM2B complex induces KSHV lytic gene expression through inducing AP-1 activity.