Drosophila Stem Cell Niches: A Decade of Discovery Suggests a Unified View of Stem Cell Regulation

Abstract

The past decade of research on Drosophila stem cells and niches has provided key insights. Fly stem cells do not occupy a special "state" based on novel "stem cell genes" but resemble transiently arrested tissue progenitors. Moreover, individual stem cells and downstream progenitors are highly dynamic and dispensable, not tissue bulwarks. Niches, rather than fixed cell lineages, ensure tissue health by holding stem cells and repressing cell differentiation inside, but not outside. We review the five best-understood adult Drosophila stem cells and argue that the fundamental biology of stem cells and niches is conserved between Drosophila and mice.

Somatic cell lineage is required for differentiation and not maintenance of germline stem cells in Drosophila testes

“…Consistent with this observation, TGF-β signals from niche cells repress the expression of Bam in GSCs in the female germline (7). Unlike the female germline however, function of Bam and deactivation of TGF-β signaling is not necessary for male GSCs to enter the TA program (19,27), suggesting that other factors are involved in instructing male GSCs to initiate differentiation.…”

“…Different aspects of the male GSC program appear to be controlled by multiple inputs from the local microenvironment at Although the model that niches serve primarily to promote stem cell self-renewal may be true for many adult stem cell systems (7,29,30), our results indicate that components of the microenvironment may play key roles that can trigger stem cell differentiation. Indeed, as we come to understand the workings of more complex niches in mammalian systems, we may find combinations of these two opposing influences, with some areas of the niche promoting self-renewal of stem cells, whereas neighboring regions drive differentiation of stem cell daughters.…”

L’intestin moyen de drosophile

“…Des avancées significatives dans la connaissance des mécanismes régulant les cellules souches et conservés chez les mammifères ont ainsi été réalisées chez la drosophile. L'étude des cellules souches germinales a mis en évidence le rôle du microenvironnement dans le contrôle du devenir des cellules souches et a permis de valider le concept de niche [5,6]. De même, le processus de division des neuroblastes (cellules progénitrices neurales partageant un grand nombre de caractéristiques avec les cellules souches) est un excellent exemple de divisions asymétriques contrôlant le renouvellement et la différen-ciation des cellules souches [7].…”

Simultaneous control of stemness and differentiation by the transcription factor Escargot in adult stem cells: How can we tease them apart?

“…Research focused on Drosophila stem cells has been instrumental in characterizing basic mechanisms of stem cell regulation, including the interactions between stem cells and their niche [10][11][12] and the role of asymmetric divisions in controlling stem cell behavior (reviewed in 13,14 ). In addition, more recent work has underscored the use of Drosophila as an excellent model system to explore the response of stem cells to various forms of physiological, metabolic and genotoxic stress, from infections to starvation and aging.…”