Melanoma Antigen Gene Protein-A11 (MAGE-11) F-box Links the Androgen Receptor NH2-terminal Transactivation Domain to p160 Coactivators

Androgen-dependent transcriptional activity by the androgen receptor (AR) and its coregulators is required for male reproductive development and function. In humans and other primates, melanoma antigen gene protein-A11 (MAGE-11) is an AR selective coregulator that increases AR transcriptional activity. Here we show that the interaction between AR and MAGE-11 is mediated by AR NH2-terminal FXXLF motif binding to a highly conserved MAGE-11 F-box in the MAGE homology domain, and is modulated by serum stimulation of mitogen-activated protein kinase phosphorylation of MAGE-11 Ser-174. The MAGE-11-dependent increase in AR transcriptional activity is mediated by a direct interaction between MAGE-11 and transcriptional intermediary factor 2 (TIF2) through the NH2-terminal region of TIF2, and by a MAGE-11 FXXIF motif interaction with an F-box-like region in activation domain 1 of TIF2. The results suggest that MAGE-11 functions as a bridging factor to recruit AR coactivators through a novel FXX(L/I)F motif-F-box interaction paradigm.