First published online March 22, 2007
Development 134, 801e (2007)
© The Company of Biologists Limited
Stonewalling stem cell differentiation
Organisms have to maintain appropriate numbers of various stem cells. Too
few can cause infertility or defective tissue regeneration; too many may
increase the risk of cancer development. Stem cells are maintained mainly by
preventing the expression of differentiation factors - sometimes this occurs
through chromatin-mediated transcriptional repression. Maines and coworkers
now report that epigenetic control mediated by the DNA-associated protein
Stonewall (Stwl) maintains female germline stem cells (GSCs) in
Drosophila (see p.
1471). The researchers show that clones of stwl-
GSCs are lost by differentiation and that overexpression of stwl
causes an expansion of GSCs. Because stwl mutants act as suppressors
of variegation (genes that prevent patchy gene silencing within tissues), they
propose that Stwl is involved in chromatin-dependent gene repression. Finally,
they show that Stwl represses the expression of many genes, some of which
contain putative binding sites for Pumilio, a translation inhibitor that,
together with Nanos, represses the translation of key differentiation factors
in GSCs. Thus, the researchers conclude, two overlapping mechanisms block GSC
differentiation.
Related articles in Development:
- Stonewalling Drosophila stem cell differentiation by epigenetic controls
- Jean Z. Maines, Joseph K. Park, Meredith Williams, and Dennis M. McKearin
Development 2007 134: 1471-1479.
[Abstract]
[Full Text]
