Stem cell beauty…yes they are so beautiful, they have amazing properties, they bring a lot of hope for future therapies…well, yes they are the stars!
However, like in everyday life, “the star” is not the only one to be the key of its own success, success is teamwork! And for stem cells, the supportive team is the stem cell niche, also called microenvironment.
Studying stem cell niches is key to understanding stem cell biology since the niche directly influences stem cell fate choices, such as proliferation and/or differentiation.
Several factors regulate stem cells within the niche: interactions between stem cells and their neighboring cells but also interactions between stem cells and the surrounding matrix components or nutritional inputs (growth factors for example). In addition, the physiochemical surrounding (pH, temperature,…) is very important within the niche.
This month in Development , Gancz and Gilboa show that the nutritional input conveyed by the insulin signalling pathway plays key roles in the development of the ovarian niche-stem cell units in Drosophila melanogaster. In this picture, we can observe Drosophila melanogaster ovaries at LL3 stage of development. When the insulin receptor is overexpressed (on the right panel), the ovary is much bigger than normal (on the left). Also, there are more terminal filaments cells (in pink), a major component of the germ stem cell niche.
Interestingly, their study shows that in addition of strongly influencing the development of the germ stem cell niche (terminal filament cells and intermingled cells), insulin signalling also regulates the number of germ stem cell precursors (ancestors of mature ovarian stem cells, in blue in the picture). So, insulin signalling contributes to ensure that germ stem cells and their niche develop coordinately.
Extensively describing niche components and understanding how they influence stem cell decisions is a major challenge in stem cell biology. Indeed, reproducing stem cell-niche interactions in petri dishes would give scientists the keys to instruct stem cells in the directions they are interested in!
D. Gancz, L. Gilboa, Insulin and Target of rapamycin signaling orchestrate the development of ovarian niche-stem cell units in Drosophila. Development, (Sep 11, 2013). doi:10.1242/dev.093773