Sci. Aging Knowl. Environ., 30 November 2005
Vol. 2005, Issue 48, p. or21


SMEDWI-2 Is a PIWI-Like Protein That Regulates Planarian Stem Cells

Peter W. Reddien, Néstor J. Oviedo, Joya R. Jennings, James C. Jenkin, and Alejandro Sánchez Alvarado

Abstract: Science 310, 1327-1330 (2005).

We have identified two genes, smedwi-1 and smedwi-2, expressed in the dividing adult stem cells (neoblasts) of the planarian Schmidtea mediterranea. Both genes encode proteins that belong to the Argonaute/PIWI protein family and that share highest homology with those proteins defined by Drosophila PIWI. RNA interference (RNAi) of smedwi-2 blocks regeneration, even though neoblasts are present, irradiation-sensitive, and capable of proliferating in response to wounding; smedwi-2(RNAi) neoblast progeny migrate to sites of cell turnover but, unlike normal cells, fail at replacing aged tissue. We suggest that SMEDWI-2 functions within dividing neoblasts to support the generation of cells that promote regeneration and homeostasis.

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Science of Aging Knowledge Environment. ISSN 1539-6150