Histone modifications and exchange during transcription: signals and mechanisms

Eukaryotic DNA is folded into an ordered nucleoprotein structure called chromatin. Dynamic alterations in chromatin structure regulate transcription (the process of producing the messenger RNA), a key step in transmitting the message encoded in the DNA. The passage of the RNA polymerase II enzyme over the chromatin template is facilitated by the sequential removal and replacement of histones, which are the core protein components of chromatin. This process is termed histone exchange, and is a key step in regulating transcription. This talk focuses on the mechanism of action of various histone modifications that are added along with transcription. We are interested the methylation and acetylation of key residues that regulate the process of histone exchange and thereby maintain a proper chromatin structure. This mechanism assumes importance as perturbations in this pathway leads to the aberrant production of non-coding RNA, which is being linked to the development of several disease states, particularly cancer.