Regulation of c-myc transcription initiation and elongation

The c-myc protooncogene plays an important role in the regulation of cellular proliferation and differentiation. Selective downregulation of c-myc expression induces differentiation of leukemic cells, whereas constitutive overexpression prevents differentiation of the same cell types. The c-myc gene is comprised of three exons, the first of which is largely untranslated. Both c-myc mRNA and the c-myc gene product have very short half-lives, resulting in a very sensitive regulation of this important gene. Both transcriptional and posttranscriptional regulation of the c-myc gene expression have been documented. Transcriptional regulation can occur at the level of transcriptional initiation or elongation. A number of c-myc promoter-binding proteins have been identified and characterized. These include positive and negative regulatory factors. It appears that the c-myc gene is very tightly regulated in response to positive and negative growth stimuli.