Epigenetic Mechanism of rRNA Gene Silencing

Here is the abstract for my literature review as promised in the

literature review topics blog.

Research over the past decade has revealed that the chromatin structure is far more than a static carrier of the genetic information encoded in the DNA as it actively and dynamically mediates regulation of processes requiring protein access to DNA, i.e. transcription, recombination and replication. Emerging evidence indicates that epigenetic factors control and regulate most nuclear processes. These factors alter chromatin structure by covalent DNA modifications, covalent histone modifications and nucleosome reorganization. A prominent case where nucleosome remodelling and histone acetylation contribute within one pathway is the silencing of rDNA promoters transcribed by RNA polymerase with targeting of the nucleolar remodelling complex (NoRC) to the rDNA promoter as initial step. NoRC is a multi-functional entity that catalyses the precise positioning of a nucleosome at the promoter but also recruits histone deacetylase (HDAC) and DNA methylase complexes which establish silent chromatin.
Raffaella Santoro and Ingrid Grummt have investigated the functional interrelationship and temporal order of NoRC-mediated chromatin remodelling, histone modification, and DNA methylation leading to rRNA gene silencing. The results of their study reveal a clear hierarchy of epigenetic events.

Have a nice and relaxing easter break. I see you all for class next tuesday.

Katharina