What makes an embryonic stem cell pluripotent? A protein known as Nanog could be a crucial player.

Embryonic stem (ES) cells have remarkable powers. They can develop into any of the thousands of different cell types found in the adult body and they can constantly replenish themselves, potentially providing an endless supply of new cells of any given type.

There is great interest in uncovering the molecular basis of these unique abilities. Now, Austin Smith and colleagues have found that the Nanog protein is fundamental to pluripotency.

Fittingly named after Tír na nÓg, the mythological Celtic land of the always young, Nanog is known to be active in embryonic stem cells. In their latest experiments, Smith and colleagues fused ES cells with neural stem cells. Levels of Nanog rose in the fused cells, switching on genes typically active in pluripotent ES cells.

Pluripotency seems to be linked to the coordinated activity of a small number of key genes, the activity of which is controlled epigenetically (by modification of DNA in key positions around the gene). Nanog appears to be able to reprogramme these epigenetic modifications, turning a partially differentiated stem cell back into a pluripotent one.

This work is particularly important as it suggests ways in which pluripotent stem cells could be created without having to harvest them from embryos.

See also

• New stem cell centre (Funding, 25 July 2006)

External links

• Silva J et al. Nanog promotes transfer of pluripotency after cell fusion. Nature 2006;441(7096):997–1001.