AR function is altered by polyglutamine expansion and by SUMO

Expansion of a polyglutamine (polyQ) tract in the gene for the androgen receptor (AR) results in partial loss of transactivation function and causes spinobulbar muscular atrophy (SBMA). Modification of AR by small ubiquitin-like modifier (SUMO) reduces AR function in a promoter context-dependent manner. We used microarrays to confirm and demonstrate loss of AR function from polyQ expansion and to test the degree to which AR function is altered by preventing polyQ AR SUMOylation. PC12 cells expressing AR10Q, AR112Q, or nonSUMOylatable AR112Q (KRKR) in the presence or absence of synthetic androgen R1881 were assessed for alterations in AR function by comparing gene expression changes with each AR variant in response to ligand.