Regulation of the Ig κ-chain enhancer by the adenovirus E1A gene products. Repression in lymphoid cells, activation in fibroblasts

Proteins encoded by early region 1A (E1A) regulate transcription of viral and cellular genes. The mechanism of this trans-activation is not understood, but is of considerable interest as an example of transcription regulation through a cellular intermediate. We have therefore studied the effect of E1A products on the activity of the κ L chain gene promoter and enhancer. By using transient and stable transfections into lymphoid and nonlymphoid cells, we found that the E1A proteins have a pleiotropic effect on the regulation of the mouse κ-chain gene enhancer. In lymphoid cells the E1A products repress κ-chain enhancer, whereas in fibroblasts, the κ-chain enhancer is activated by the E1A products whether the E1A gene is in an extrachromosomal location or stably integrated in the genome. Furthermore, a functional κ-chain promoter, containing the octanucleotide and 'TATA' sequences is needed in order to be transcribed in E1A-producing cells. This ability of E1A products to negatively and positively regulate κ-chain transcription may reflect a more general phenomenon in which a given cellular protein could participate in a variety of different cellular controls.