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DE-cadherin (green) sticks GSCs (dark red and blue) to cap cells (bright red). Xie/AAAS

Stem cells exist in a number of adult tissues, but the molecular requirements for keeping them in place and undifferentiated are not clear. Now, Xiaoqing Song, Ting Xie (Stowers Institute for Medical Research, Kansas City, MO), and colleagues find that, in the Drosophila ovary, the adhesion proteins DE-cadherin and Armadillo work together to recruit and keep the germline stem cells (GSCs) in their niche.

The proteins mediate adhesion between germ cells and follicle cells in the ovary, so Xie reasoned that they might be involved in anchoring the GSCs to cells at the distal tip of the ovary, called cap cells. Sure enough, DE-cadherin and Armadillo proteins colocalize in narrow strips between the cap cells and the GSCs.

Genetics suggests that this localization reflects function. Within one week of inducing expression of either a deletion mutant or a weak allele of DE-cadherin, over half of the GSCs left their niche, implying that adhesion is required for GSC maintenance. Similar results followed with armadillo.

Based on the work of others, Xie believes that DE-cadherin and Armadillo (or its mammalian homologue ß-catenin) function in a similar manner in a number of other stem cell niches. But they may not act alone. Xie and colleagues found that if primordial germ cells—which are destined to become GSCs—lack DE-cadherin, they are far less likely to be recruited into the stem cell niches, but they do occasionally make it there. This means that DE-cadherin is important for the recruitment of GSCs to their niche as well as for their maintenance, but it also implies that additional recruiting mechanisms are at work.

Reference:

Song, X., et al. 2002. Science. 296:1855–1857.[Abstract/Free Full Text]

Rabiya Tuma

rabiya{at}nasw.org

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This Article PDF (Full Text) PPT slides of all figures Alert me when this article is cited Services Email this article Similar articles in this journal Alert me to new content in the JCB Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Tuma, R. Search for Related Content PubMed Articles by Tuma, R. Social Bookmarking                      What's this?