Molecular mechanisms involved in transcription regulation of protein-encoding genes

Transcription regulation plays a major role in the repertoire of gene expression from a genome in development and in many other biological processes. In eucaryotes, transcription of protein encoding genes is catalyzed by RNA polymerase II. Regulation of this reaction requires both cis-acting elements and trans-acting factors.;I have analyzed nucleotide sequences required for the transcription regulation of the c-myb proto-oncogene. It has been reported that the expression of c-myb is regulated by a transcriptional block in intron 1 during elongation. My research shows that this block maps at position Tm, approximately 1700 bp from the start of the intron. The 5;I have also analyzed the function of human p300 protein as a coactivator for MyoD. The p300 protein is a cellular target of adenovirus E1A oncoprotein and a potential transcription coactivator. E1A represses MyoD-mediated E box enhancer activity. This repression by E1A requires its interaction with p300. Further, p300 interacts with MyoD and potentiates MyoD transactivation. p300 is also able to interact with TBP and TFIIB. The ability of p300 to communicate between the basal transcription complex and DNA-binding transactivator MyoD in transcription modulation defines p300 as a transcription coactivator for MyoD. This finding suggests a mechanism by which p300 could be involved in muscle differentiation.