ACTIVATION OF THE MURINE MONOCYTE-MACROPHAGE CELL-LINE, J774A(1) BY POLY(A)-POLY(U) .1. BINDING OF POLY(A)-POLY(U) AND INDUCTION OF OLIGO-2',5'-ADENYLATE SYNTHETASE

Binding and internalization of the synthetic double-stranded complex p oly(A) . poly(U) were studied on a murine monocyte/macrophage cell lin e J774A1. Poly(A) . poly(U) increased in a dose-dependent fashion the oligo-2',5'-adenylate synthetase demonstrating that those cells were r esponsive to this agonist. Binding of P-32!poly(A) . P-32!poly(U) to the cells reached an apparent kinetic equilibrium within 4 h and was saturable (apparent K(d) = 9.99 +/- 0.09 . 10(-2) g/l and B(max) 13.3 +/- 5.3 . 10(-3) g/l per 10(6) cells) and temperature-dependent. The b inding of poly(A) . poly(U) was competitively inhibited by various pol ynucleotides but not by other structurally unrelated compounds. Analys is of cell-associated P-32!poly(A) . P-32!poly(U) demonstrated a min imal degradation of this polyribonucleotide over a 4-h incubation peri od. Autoradiography of cells incubated with H-3!poly(A) . H-3!poly(U ) revealed that poly(A) . poly(U) was internalized and migrated to cel l nuclei. These results suggest that poly(A) . poly(U) is internalized in J774A1 cells via an endocytotic process.