A VITAL gene that defends us against cancer has been found in one of the simplest of animals 鈥� placozoans. The finding shows that p53, sometimes described as the 鈥済uardian of the genome鈥�, has been around for over 1 billion years.
Placozoans鈥� millimetre-long bodies are just three cells thick and have no muscles, nervous system or organs. Yet they have a version of p53 that is strikingly similar to ours, David Lane, of Cancer Research UK, reports in research to be published in Cell Cycle.
In humans, the protein it codes for, p53, detects and deals with damaged DNA that could trigger cancers. Faulty or inactive copies of the gene greatly increase the chances that a cell will become cancerous.
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It is not clear whether p53 has the same function in placozoans. There is evidence to suggest the gene originally controlled stem cells or immune response, and was only later co-opted to defend animals against rogue cells when they became large and long-lived.
However, human and placozoan versions of p53 share key features, including regions that allow it to attach to DNA and other proteins. This suggests it has interacted with a similar network of partner genes since the dawn of the animal kingdom.