Synthesis of New Proteins Associated with the Induction of Interferon in Human Fibroblast Cells

The relative amounts of translatable cellular mRNAs and newly synthesized cellular proteins were examined in poly(I)· poly(C)-induced human fibroblast cells early during induction. At this time interferon and interferon mRNA synthesis are maximal and cells have not acquired their antiviral state. Translation of the mRNA from poly(I)· poly(C)-induced cells in a wheat germ cell-free system led to the synthesis of a [35S]methionine-labeled 22,000-dalton protein that is precipitated by antiserum to highly purified human fibroblast interferon. The synthesis of this protein was detected only with the mRNA preparations that, when translated in Xenopus oocytes, coded for the synthesis of biologically active human interferon. Two-dimensional gel analysis of the [35S]methionine-labeled polypeptides translated from the total mRNA of the induced and uninduced cells revealed the presence of 23 new proteins that were translated from mRNAs of the induced cells but not from the mRNAs of the controls. These polypeptides ranged from 15,000 to 70,000 daltons. Thirteen of these proteins were detected in induced cells labeled with [35S]methionine. It is concluded that, in human fibroblasts, poly(I)· poly(C) induces, in addition to interferon, the synthesis of a variety of ``interferon-associated'' proteins.