Trans-activation of transcription, from promoters containing immunoglobulin gene octamer sequences, by myeloma cell mRNA in Xenopus oocytes.

To study factors required for immunoglobulin gene transcription hybrid promoters were made by linking octamer elements to a Xenopus albumin gene construct containing only 50bp of the albumin gene promoter. When injected into oocytes these hybrid promoters directed transcription far less efficiently than the unmodified 50bp albumin gene promoter fragment. Activity of the hybrid promoter, but not the unmodified albumin promoter, could be stimulated by preinjection of poly(A)+ RNA from NS1 myeloma cells. This stimulation may be caused by translation of the NS1 poly(A)+ RNA into transcription factors that act on the octamer. Both the reduction in transcription caused by octamer insertion and the extent of the inducibility by NS1 RNA are greater when two, rather than one, octamers are inserted.