More on Adult Stem Cells

MicroRNAs:

Johns Hopkins Kimmel Cancer Center scientists have found a set of "master switches" that keep adult blood-forming stem cells in their primitive state. ...

The scientists located the control switches not at the gene level, but farther down the protein production line in more recently discovered forms of ribonucleic acid, or RNA. MicroRNA molecules, once thought to be cellular junk, are now known to switch off activity of the larger RNA strands which allow assembly of the proteins that let cells grow and function.

"Stem cells are poised to make proteins essential for maturing into blood cells, but microRNAs keep them locked in their place," says cancer researcher Curt Civin, M.D., Ph.D., who led the study. The journal account will appear online the week of February 5 in the early edition of the Proceedings of the National Academy of Sciences.