Regulation of c-myc and immunoglobulin kappa gene transcription by promoter-proximal pausing of RNA polymerase II.

In normal cells, the proto-oncogene c-myc is regulated by promoter-proximal pausing of RNA polymerase II (pol II). In Burkitt lymphoma cells, c-myc is chromosomally translocated to one of the three immunoglobulin (Ig) gene loci and its transcription is driven constitutively by Ig enhancers. Promoter-proximal pausing of pol II is abolished on the translocated c-myc allele. This raised the question whether induction of Ig gene transcription also involves activation of promoter-proximal paused pol II. Here we have studied the transcriptional activation of a functionally rearranged Ig kappa gene in the mouse pre B cell line 70Z/3. We show that pol II pauses approximately 50 bp downstream of the transcriptional start site of the uninduced Ig kappa gene.