P53 gene

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p53 (TP53) is a tumour suppressor gene, sometimes dubbed the 'guardian of the genome'.[1] First described in 1979,[2] the expressed protein is thought to exert its function by monitoring the integrity of the genome and preventing the passage of DNA damage through co-ordinating several mechanisms, e.g. inducing apoptosis, inducing cell cycle arrest or facilitating DNA repair by delaying the cell cycle.

It has been conserved by natural selection through a very long evolutionary history - a sign of huge importance.

Mutations in the p53 tumour suppressor gene are found in over 50% of human tumours, including 60% of lung cancers.[3]. A rare, autosomally dominant syndrome, called Li-Fraumeni syndrome results in early onset of several types of cancers.

A theory of cancer genesis is of accumulation of damage, sequentially, to several intracellular control systems each of which would prevent the initial cell running wild, which might still be headed off by an immune system reaction, but in a proportion of instances is not, leading to propagation of the clone of tumour cells. The myriad pathways of oncogenesis thus pass through a number of common gateways.

The p53 system is one of the more ancient, fundamental and powerful of these stop-systems and if it is knocked out uncontrolled cell division becomes likely.

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