Understanding the Niche

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Science  09 Nov 2012:
Vol. 338, Issue 6108, pp. 723
DOI: 10.1126/science.338.6108.723-d

Stem cells have the special ability to self-renew or undergo preprogrammed differentiation. The stem cell niche plays an important role in regulating this decision. If self-renewal proceeds uncontrollably, tumors can result. In the testes of Drosophila, a model used to understand niche–stem cell interactions, the niche is composed of the apical hub, which is important for the regulated division of its two stem cell populations: the germline stem cells (GSCs) and the cyst stem cells (CySCs). Prior studies had suggested that CySCs also serve as a niche to maintain GSCs; however, Lim and Fuller showed that after ablation of the CySCs and their progeny, early germ cells with GSC characteristics were still maintained. In particular, cells located near the apical hub were able to maintain the properties of GSCs in the absence of CySCs. Although the CySCs and cyst cells were not needed to maintain GSCs, they were necessary for their progression to the transit-amplifying stage, where the cells go through mitotic divisions before terminal differentiation. Hence, contrary to some prior conclusions, CySCs are not needed for GSC self-renewal but instead may provide signals to allow their progression through the transit-amplifying–stage divisions. This work highlights the intricate nature of the relationships between stem cells and the surrounding somatic cells.

Proc. Natl. Acad. Sci. U.S.A. 10.1073/pnas.1215516109 (2012).

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