Free Republic

miRNA-145 represses Klf-4, Oct4 and Sox2, and is repressed by Oct4How pluripotency is controlled is one of biology's major puzzles. New research led by Kenneth Kosik of the University of California, Santa Barbara reveals not only a new piece in the puzzle but also how some major pieces fit together.A set of transcription factors — Klf4, Oct4 and Sox2 — is sufficient to reprogram specialized cells to pluripotency. As pluripotent cells take on a differentiated fate, these transcription factors disappear. Kosik found that one microRNA (miRNA) is able to repress all three of these proteins.Although these small RNA molecules can...

June 21, 2007, 5:00 a.m. Beginning of the End?President Bush moves to redefine the stem-cell debate. By Yuval Levin Since it began almost a decade ago, the debate over embryonic-stem-cell research has been driven by two simple premises: embryonic stem cells are uniquely valuable for their potential to be turned into the other cell types of the body, and they are derived through the destruction of embryos. The first premise — the potential of the cells — explains the desire to explore their uses. And the second — the destruction of nascent lives involved in getting the cells —...