Induction of NF-κB DNA-Binding Activity during the G₀-to-G₁ Transition in Mouse Fibroblasts

Abstract

A DNA-binding factor with properties of NF-κB and another similar activity are rapidly induced when growth-arrested BALB/c 3T3 cells are stimulated with serum growth factors. Induction of these DNA-binding activities is not inhibited by pretreatment of quiescent cells with the protein synthesis inhibitor cycloheximide. Interestingly, the major NF-κB-like activity is not detected in nuclear extracts of proliferating cells, and thus its expression appears to be limited to the G₀-to-G₁ transition in 3T3 cells. These DNA-binding activities bind many of the expected NF-κB target sequences, including elements in the class I major histocompatibility complex and human immunodeficiency virus enhancers, as well as a recently identified NF-κB binding site upstream of the c-myc gene. Furthermore, both the class I major histocompatibility complex and c-myc NF-κB binding sites confer inducibility on a minimal promoter in 3T3 cells stimulated with serum growth factors. The results demonstrate that NF-κB-like activities are immediate-early response proteins in 3T3 cells and suggest a role for these factors in the G₀-to-G₁ transition.