FIGURE 5.

PARP-1 promotes the poly-ubiquitination and degradation of FOXP3. A, HEK 293T cells were co-transfected with plasmids encoding for PARP-1, FOXP3, Ub, and Stub1. Cell lysates were examined by immunoblotting (IB) with different antibodies as indicated. B, HEK 293T cells were co-transfected with plasmids encoding for PARP-1, FOXP3, Ub, and Stub1. Before harvesting, these cells were treated with 5 μm MG132 for 4 h. The ubiquitin pulldown assay for His-tagged Ub was performed as described under “Experimental Procedures.” C, human primary Treg cells were immunoprecipitated (IP) with anti-Ub antibody and analyzed by Western blotting. Data represent at least two independent experiments.