DMMC Course: UNRAVELLING CHROMATIN & THE ROLE OF EPIGENETICS IN DISEASE

1000-1030 Tuesday 25 April 2006. UCD Conway Institute Lecture Theatre

Chromatin structure
Dr John Baugh (UCD Conway Institute of Biomolecular & Biomedical Research)
Dr Jenny Orr (UCD Conway Institute of Biomolecular & Biomedical Research)

In the eukaryotic nucleus, DNA is organised in association with histone proteins in a hierarchy of structures which work together to obtain the level of compaction required for a nucleus with a diameter of 10µm to accommodate 2m of DNA. These structures are collectively known as chromatin, and it is on this scaffold that many molecular events occur.

We hope to provide an overview of chromatin structure, from the organisation of DNA and histone components in the nucleosome unit, to higher order chromatin distribution, which is present in the nucleus as a delicate balance of euchromatic or heterochromatic regions. The dynamic nature of the chromatin structure will also be discussed, including the fundamental ability of chromatin to ‘relax’, allowing temporary access for transcription factors and other cellular regulators to specific regions of the DNA sequence. This will be considered in terms of the normal regulation of cellular processes, and also in the context of the disrupted nuclear topology in cancer.

Epigenetic modifications have been found to alter DNA and histone interactions and may therefore contribute to the regulation of chromatin architecture. The disruption of these essential controls may therefore play a key role in the disruption of nuclear phenotype observed in cancer cells.