Germline Stem Cells Anchored by Adherens Junctions in the Drosophila Ovary Niches

Abstract

How stem cells are recruited to and maintained in their niches is crucial to understanding their regulation and use in regenerative medicine. Here, we demonstrate that DE-cadherin-mediated cell adhesion is required for anchoring germline stem cells (GSCs) in their niches in the Drosophila ovary. Two major components of this adhesion process, DE-cadherin and Armadillo/beta-catenin, accumulate at high levels in the junctions between GSCs and cap cells, one of the niche components. Removal of these proteins from GSCs results in stem cell loss. Furthermore, DE-cadherin is required for recruiting GSCs to their niche. Our study demonstrates that anchorage of GSCs in their niche by DE-cadherin-mediated adhesion is important for stem cell maintenance and function.

The Drosophila ovary: an active stem cell community

“…First, if the two daughters of a GSC following cell division are positioned where GSCs are normally located, both of them adopt the GSC fate [15]. Second, GSCs have to be directly anchored to cap cells through adherens junctions in order to continuously self-renew [16]. Third, TFs and cap cells express several genes that are important for controlling GSC self-renewal [15,[17][18][19][20][21][22].…”

Genetic dissection of a stem cell niche: The case of the Drosophila ovary

“…Our observations demonstrate the value of bab1-Gal4 for studying genes involved in stem cell niche morphogenesis. This approach could be applied to other genes such DE-cadherin (shg) or armadillo (arm), which have been proposed to play an adhesive role in the morphogenesis of terminal filaments and the anchoring of GSCs into the niche (Song et al, 2002).…”

“…1B). CpCs, located between GSCs and the anterior terminal filament (TF), accumulate high levels of the Drosophila homologue of ␤-catenin (Song et al, 2002) (Fig. 1C).…”

“…Ectopic expression of dpp results in the formation of large GSClike tumors, suggesting that dpp is both necessary and sufficient to prevent GSC differentiation (Xie and Spradling, 1998). It is still uncertain which somatic cells in the GSC niche are responsible for the expression of niche signals such as dpp and gbb, although CpCs are likely candidates given the importance of their association with GSCs for germline maintenance (Song et al, 2002), their expression of dpp mRNA (Xie and Spradling, 2000), and the close correlation between CpC and GSC numbers as germaria age (Xie and Spradling, 2000). TFCs express several genes required for stem cell maintenance including piwi and Yb (Wong et al, 2005).…”

Régulation des cellules souches de la lignée germinale

“…Les cellules somatiques environnantes jouent un rôle fondamental dans cette asymétrie. Il existe en effet des jonctions, adhérentes et communicantes, entre les CSG et les cellules somatiques afin de maintenir une des cellules filles à leur contact qui conservera les caracté-ristiques de CSG [7,8]. Pour preuve, l'absence de E-cadhérine, qui est le composant principal des jonctions adhérentes, entraîne le détache-ment des CSG de la niche, induisant ainsi leur perte par différenciation et donc la stérilité des mouches.…”