The interactions of androgen receptor with poly(A)-containing RNA and polyribonucleotides

The androgen receptor from mouse kidney cytosol binds not only to DNA but also to RNA as assayed by competition with DNA-cellulose centrifugation or by direct binding with agarose-polynucleotides. The dihydrotestosterone-receptor complex interacts more strongly to poly(A)-containing mRNA than to native natural DNA; it binds much more tightly to synthetic poly(G) than to natural DNA and other homopolyribonucleotides such as poly(U), poly(A), or poly(C). Poly(U) is moderately effective in competing for the complex, whereas poly(A) and poly(C) re not effective. Competition studies with heteropolyribonucleotides show that polymers containing G are most effective on binding to the androgen receptor, whereas those containing U are moderately effective, and those containing only A and C are least effective. Several analogues of poly(G), such as poly(X), poly(I), and poly(m7G) interact very well with the dihydrotestosterone-receptor with some differences in the bindings. A double-stranded polymer, poly(I) . poly(C) competes poorly for the androgen receptor. The observations that the androgen receptor binds to RNA and interacts with polyribonucleotides selectively suggest that androgen receptor-RNA interaction could play important roles in gene regulation.