Acetylation regulates Jun protein turnover in Drosophila

• Drosophila Jun protein, Jra, is acetylated in vivo.
• CBP and Sir2 regulate Jra acetylation in vivo.
• Acetylation is required for Jra degradation upon osmotic stress.
• Acetylation facilitates Jra poly-ubiquitination.
• Phosphorylation counteracts the acetylation of Jra.

C-Jun is a major transcription factor belonging to the activating protein 1 (AP-1) family. Phosphorylation has been shown to be critical for c-Jun activation and stability. Here, we report that Jra, the Drosophila Jun protein, is acetylated in vivo. We demonstrate that the acetylation of Jra leads to its rapid degradation in response to osmotic stress. Intriguingly, we also found that Jra phosphorylation antagonized its acetylation, indicating the opposite roles of acetylation and phosphorylation in Jra degradation process under osmotic stress. Our results provide new insights into how c-Jun proteins are precisely regulated by the interplay of different posttranslational modifications.