Correct positioning of stem cells within their niche is essential for tissue morphogenesis and homeostasis. How stem cells acquire and maintain niche position remains largely unknown. Here, we show that a subset of brain neuroblasts (NBs) in Drosophila utilize Phosphoinositide 3-kinase (PI3-kinase) and DE-cadherin to build adhesive contact for NB niche positioning. NBs remain within their native microenvironment when levels of PI3-kinase activity and DE-cadherin are elevated in NBs. This occurs through PI3-kinase-dependent regulation of DE-Cadherin-mediated cell adhesion between NBs and neighboring cortex glia, and between NBs and their ganglion mother cell daughters. When levels of PI3-kinase activity and/or DE-Cadherin are reduced in NBs, NBs lose niche position and relocate to a non-native brain region that is rich in neurosecretory neurons, including those that secrete some of the Drosophila insulin-like peptides. Linking levels of PI3-kinase activity to the strength of adhesive attachment could provide cancer stem cells and hematopoietic stem cells with a means to cycle from trophic-poor to trophic-rich microenvironments.
Keywords: DE-Cadherin; Drosophila; Neuroblast; Niche; PI3-kinase; Shotgun; Stem cell.
© 2017. Published by The Company of Biologists Ltd.