News Release

Researchers discover that DNA packaging in living cells is dynamic

Discovery could help scientists to understand how cells 'remember' which genes to switch on or off

Peer-Reviewed Publication

Imperial College London

Scientists from Imperial College London, the Medical Research Council, Cancer Research UK and the Hammersmith Hospital have discovered an important aspect of how heterochromatin, the wrapping around DNA, works.

The researchers, whose work is published today in Science, discovered that heterochromatin is dynamic, constantly wrapping and unwrapping around DNA, and not static as previously thought. This packaging is one way in which the cell limits which genes are turned on, 'locking-in' different patterns of gene expression in different cell types.

Dr Richard Festenstein from Imperial College London and the MRC Clinical Sciences Centre, at the Hammersmith Hospital comments: "Although this research improves our basic understanding of how cells 'remember' which genes to 'switch on or off', it could also help us understand diseases which are linked to inappropriate 'switching', such as cancer, and several inherited diseases."

Previously heterochromatin was thought to be a static structure, which stabilised crucial aspects of nuclear organisation and prohibited access to transcription factors. Heterochromatin protein 1 (HP1b) is a key component of condensed DNA, and is strongly implicated in gene silencing.

The researchers tagged HP1b with a green fluorescent protein to allow them to follow its movement, and discovered that HP1b moves rapidly within and between the euchromatin (loosely packaged DNA) and heterochromatin (densely packaged DNA) of mouse immune cells.

Dr Festenstein adds: "The previous view that heterochromatin was a sort of static 'molecular-glue' has been shattered, revealing a dynamic way of regulating access of crucial factors to DNA.

"There are many protein factors which need to get to the DNA, such as DNA repair factors, factors which switch on genes and factors required for DNA replication when each cell divides. We also discovered that immune cell activation greatly increased this HP1b mobility, indicating that such a process may facilitate the remodelling of heterochromatin and thereby regulate the access these key factors to the DNA."

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1.     The research was carried out at the MRC Clinical Sciences Centre, based at Imperial College London's Faculty of Medicine, Hammersmith Hospital.
2.      Consistently rated in the top three UK university institutions, Imperial College London is a world leading science-based university whose reputation for excellence in teaching and research attracts students (10,000) and staff (5,000) of the highest international quality. Innovative research at the College explores the interface between science, medicine, engineering and management and delivers practical solutions that enhance the quality of life and the environment - underpinned by a dynamic enterprise culture. Website: www.ic.ac.uk.
3.      The Medical Research Council (MRC) is a national organisation funded by the UK tax-payer. Its business is medical research aimed at improving human health; everyone stands to benefit from the outputs. The research it supports and the scientists it trains meet the needs of the health services, the pharmaceutical and other health-related industries and the academic world. MRC has funded work which has led to some of the most significant discoveries and achievements in medicine in the UK. About half of the MRC's expenditure of over £412 million is invested in its 50 Institutes, Units and Centres, where it employs its own research staff. The remaining half goes in the form of grant support and training awards to individuals and teams in universities and medical schools. Web site at: http://www.mrc.ac.uk
4.      Fifty years after the momentous discovery of the structure of DNA, which was the culmination of research by Medical Research Council scientists, Maurice Wilkins and Rosalind Franklin in London, and James Watson and Francis Crick in Cambridge, the world celebrates one of the most significant landmarks of 20th century science. For more information about events and news please visit the www.mrc.ac.uk or www.dna50.org.uk


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