Transcriptional ERRgamma2-mediated activation is regulated by sentrin-specific proteases.

Modification With SUMOs (small ubiquitin-related modifiers) has emerged as in important means of regulating the activity of transcription factors, often by repressing their activity. The ERR gamma [oestrogen receptor-related receptor gamma; ERR3 or NR3B3 (nuclear receptor subfamily 3, group B, gene3)] is 11 Constitutively active orphan nuclear receptor. A PDSM, (phosphorylation-dependent sumoylation motif) is located in the close vicinity of the N-terminally located ERR gamma 2-specitic AF-1 (activation function-1). Its function can be replaced by an NDSM (negatively charged amino acid-dependent sumoylation motif). A mutational analysis reveals that ERR gamma 2 activity is modulated through sumoylation of a lysine residue at position 40, which ill turn is regulated by phosphorylation. Phosphorylation at the +5 position relative to the sumoylation target is directly Visualized by a high-resolution EMSA (electrophoretic mobility-shift assay). Sumoylation represses the activity of ERR gamma both with and without forced expression of the PGC-1 beta (peroxisome-proliferator-activated receptor gamma co-activator-1 beta). Fusion proteins of a heterologous DNA-binding domain with the ERR gamma 2 N-terminus demonstrate the function of the PDSM as the RF-1 (repression function-1) for the neighbouring AF-1. De-repression is achieved by co-expression of sentrin/SENP (sentrin-specific protease) family members. Together, our results demonstrate reversible phosphorylation-dependent sumoylation as a means to regulate the activity of an orphan nuclear receptor.