Spinobulbar muscular atrophy (SBMA) is an X-linked disease characterized by degeneration of motor neurons, muscle atrophy, and progressive weakness. It is caused by a polyglutamine (polyQ) expansion in the androgen receptor (AR), a transcription factor that is activated upon hormone binding. The polyQ expansion in AR causes it to form intracellular aggregates and impairs transcriptional activity. Intriguingly, SUMOylation (where SUMO indicates small ubiquitin-like modifier) of AR inhibits its transcriptional activity and reduces aggregation of the polyQ form of this protein, but it is unclear whether SUMOylation plays a pathogenic or protective role in SBMA. In this issue of the
Tim J. Craig, Jeremy M. Henley