An ancient and seldom-studied gene is critical for planarian flatworm regeneration, scientists at Northwestern University and the Massachusetts Institute of Technology have found.

The gene, called notum, plays a key role in the regeneration decision-making process. Protein from this gene determines whether a head or tail will regrow at appropriate amputation sites, the researchers said.

The researchers also found that notum controls a widely used biochemical circuit, Wnt signaling, to promote proper regeneration. This ancient signaling circuit operates in all animals and controls many processes in development and disease, including tissue repair and cancer progression.

The ability of planarians to regenerate any missing tissues after injury depends on a pool of adult stem cells. The researchers said that by studying this worm they hope to understand the molecular processes that naturally allow stem cell-mediated tissue repair in higher animals.

Christian P. Petersen, Peter W. Reddien, Polarized notum Activation at Wounds Inhibits Wnt Function to Promote Planarian Head Regeneration, Science, 2011; 332 (6031): 852-855 DOI: 10.1126/science.1202143