Figure 5. GCN5 switches substrate in a cAMP- and CITED2-dependent manner.

(a) Immunoblot analysis of the effects of FLAG-CITED2 expression or pCPT-cAMP treatment (for 1 h) in AML12 cells on the HAT activity of immunoprecipitated Myc epitope-tagged GCN5 assayed in vitro with histone H3 as substrate. (b) Effects of haemagglutinin epitope (HA)-tagged CITED2 expression in AML12 cells on the acetyltransferase activity of immunoprecipitated FLAG-GCN5 assayed in vitro with histone H3 and a His₆-tagged NH₂-terminal fragment of PGC-1α as substrates. (c) Interaction of GCN5 with PGC-1α or histone H3 was assessed by PLA in primary hepatocytes expressing either Myc-GCN5 with FLAG–PGC-1α (top) or FLAG-GCN5 alone (bottom) and exposed (or not) to pCPT-cAMP for 1 h. PLA signals (red dots) represent proximity (<40 nm) of GCN5 and either PGC-1α (top) or histone H3 (bottom). Nuclei are stained blue with 4′,6-diamidino-2-phenylindole. Scale bars, 10 μm. All data are representative of at least three independent experiments. Adenoviral vectors were used for these experiments.