Interleukin 6 enhances a cellular activity that functionally substitutes for E1A protein in transactivation.

An interleukin 6 (IL-6)-regulated cellular activity in HepG2 cells is found to functionally substitute for the transcriptional transactivator product of the adenovirus transforming gene E1A in transactivating E1A-dependent and E1A-responsive viral early genes. Mutant viruses deficient in E1A expression replicate in HepG2 cells. Induction with IL-6 leads to significant enhancement of synthesis of viral early E1B and E2ae mRNAs by greater than 30-fold and increases viral replication to the wild-type levels. The E1A-substituting activity activates E1A-responsive promoters in transient transfection, and this transcriptional activity is regulated by IL-6 induction. Formation of distinct protein-promoter complexes by binding of proteins in nuclear extracts prepared from HepG2 cells to the E1A-dependent E2ae promoter further supports the possibility that this activity may be a nuclear component in the IL-6 signal transduction pathway.