A lack of commitment for over 500 million years: conserved animal stem cell pluripotency.

Stem cells, both adult and germline, are the key cells underpinning animal evolution. Yet, surprisingly little is known about the evolution of their shared key feature: pluripotency. Now using genome-wide expression profiling of pluripotent planarian adult stem cells (pASCs), Önal et al (2012) present evidence for deep molecular conservation of pluripotency. They characterise the expression profile of pASCs and identify conserved expression profiles and functions for genes required for mammalian pluripotency. Their analyses suggest that molecular pluripotency mechanisms may be conserved, and tantalisingly that pluripotency in germ stem cells (GSCs) and somatic stem cells (SSCs) may have had shared common evolutionary origins.