Chapter Five – Intestinal Stem Cells: A Decade of Intensive Research in Drosophila and the Road Ahead

Since the molecular characterization of Drosophila midgut progenitors in 2006, a few hundred articles studying fly intestinal stem cells have already been published. There was a relative lag phase in creating new knowledge until 2009, when at least 20 papers per year started being published on the subject and at least 40 per year since 2013. Here, we ponder on the substantial literature prior to intestinal stem cell molecular identification, including intestinal stem cell development and evolutionary origin, and describe the milestones achieved since then with an emphasis on their impact on biomedical research. The existing literature illuminates aspects of intestinal stem cell function in terms of homeostasis and disease. We discuss key findings on (a) the genetic markers of stem cells, their asymmetric or symmetric divisions and their progeny, (b) signalling pathways or networks and organ communication, (c) bacterial infections and microbiota, (d) dietary factors and drugs and (e) ageing. The accumulated knowledge provides lessons relevant to intestinal hyperplasia, dysplasia and intestinal cell metastasis, signalling pathway integration, the role of regenerative inflammation in host defence and tumorigenesis, the role of diet and the potential for translational therapeutics through drugs against intestinal inflammation, tumours and ageing.