Profile: Scientist, SickKids Research Institute
Department: Molecular Genetics, University of Toronto
Lab: Pearson Lab
Our main focus is how Adult Stem Cells make their correct cellular lineage in space and time to replace the exact number and type of cells lost to physiological turnover (homeostasis) or injury (regeneration) and we use the freshwater planarian (flatworm) to understand this question. Planarians offer a unique system to study stem cell lineage production in adult animals in vivo. We focus on 2 fundamental questions in stem cell biology. First, how do stem cells maintain proliferative control in their lineage to ensure that the correct numbers of differentiated cells are produced? To answer this question, we have been testing the function of planarian homologs of human tumor suppressor genes where we find that well known tumor suppressor pathways such as PTEN, p53, and Retinoblastoma function similarly in planarians. Second, we use the regenerative ability of planarians to understand more about stem cell competence and multipotency. For example, when a small piece of a planarian tail is amputated, that tail fragment will regenerate all missing anterior structures in the span of about 10 days. During this process, stem cells that were located in the tail must re-acquire spatial identity and make anterior structures which they have not previously made such as the brain. Our goal is to understand how spatial patterning is used in planarians, and then how spatial patterning is translated by the stem cells/progeny into differentiated cell types during the regeneration of complex tissues.