Intestinal stem cells in Nothobranchius furzeri

Aging can be defined as the product of cellular decline and tissue dysfunction over time. Tissue homeostasis, which is the maintenance of proper tissue structure by regulating the balance between cell proliferation and cell death, is critically involved in aging processes Stem cells are pivotal players in this dynamic process. They may become exhausted throughout life meaning that their numbers decline and/or their potential to give rise to differentiating cells decreases. Stem cells of the intestinal tract are one of the best-studied stem cells. Intestinal stem cells (ISCs) were predominately studied in rodents and ISCs were found to give rise to all cell types of the intestinal epithelium. Further, it was discovered which molecular factors are responsible for ISC maintenance, proliferation and regeneration. It would be highly interesting to study aging of ISCs during the entire lifespan of animals. However, mice are rather long-lived whereas a short-lived model system would be preferred. In this project, we will use the novel aging research model system Nothobranchius furzeri in order to study aging of ISCs. Its lifetime of 10 weeks is the shortest life span of all vertebrate model systems known so far. In the proposed project, we aim to address the following questions: a) How is the intestinal tract of N. furzeri structured? This is a prerequisite because information of intestinal architecture is lacking. b) Where are the ISCs located? c) Which molecular markers are involved in ISC regulation? Here, we will test factors known from mammals to be specific for ISCs and probe for their presence in N. furzeri. d) Having accomplished these tasks, we have finally the pre-requisites at hand to go on and study possible changes in number and proliferative capacity of ISCs during aging of the fish. Most of the methods we intend to apply are established standard techniques and include anatomy, histology, molecular and immunological methods to detect proteins and nucleic acids on sections. In addition, labelled components of DNA will be administered to live fish where they will become incorporated into DNA during cell divisions and thus be informative of the proliferative status of cells. With the proposed project, we will gain basic insights in the aging process of intestinal stem cells. The obtained information will enable us to perform follow-up studies where we will learn more about the molecular mechanisms that influence aging of ISCs. Ultimately, we might be able to influence ISCs such that they maintain a youthful state over longer periods thus to retard aging processes in the intestine. We expect that findings of studies on ISCs of N. furzeri will be relevant for humans and may contribute to development of drugs to ameliorate intestinal homeostasis and regeneration in aging and disease.