Disrupted amino- and carboxyl-terminal interactions of the androgen receptor are linked to androgen insensitivity

We have compared the functional consequences of seven single-point mutation s in the ligand-binding domain (LBD) of the androgen receptor (AR). The mut ations span helices 3 to 11 and are present in patients suffering from andr ogen insensitivity syndromes (AIS) and other male-specific disorders. The m utants, except M742V, bound to androgen response elements in vivo and in vi tro and showed a testosterone-dependent conformational change. With regard to functional activity, the mutant M742V had severely blunted ability to tr ansactivate or exhibit the androgen-dependent amino/carboxyl-terminal (N/C) interaction; mutants F725L, G743V, and F754L showed reduced transactivatio n potential and attenuated N/C interaction; and mutants V715M, R726L, and M 886V had minor functional impairments. The mutants belonging to the first t wo groups also displayed reduced response to coexpressed GRIP1. In addition , mutations of amino acids M894 and A896 in the putative core activation do main 2 (AF2) in helix 12 confirmed that this helix is important for N/C int eractions. Thus, amino acids located between helices 3 and 4 (F725 and R726 ), in helix 5 (M742, G743, and F754), and in helix 12 (M894 and A896) play critical roles in mediating the N/C interaction of AR. The data also show t hat disrupted N/C interaction is a potential molecular abnormality in AIS c ases in which LBD mutations have not resulted in markedly impaired ability to bind androgen.