TY - JOUR T1 - A shielded irradiation assay to investigate mechanisms of <em>in vivo</em> stem cell migration in planarians JF - bioRxiv DO - 10.1101/080853 SP - 080853 AU - Prasad Abnave AU - Ellen Aboukhatwa AU - Nobuyoshi Kosaka AU - James Thompson AU - Mark A. Hill AU - A. Aziz Aboobaker Y1 - 2016/01/01 UR - http://biorxiv.org/content/early/2016/10/14/080853.abstract N2 - The migration of stem cells is an essential process underpinning the physiology of all metazoan animals. In order for tissues to be maintained, homeostatic signaling mechanisms must allow stem cells or their progeny to arrive at the correct position and differentiate into replacement cells. This need is even more acute after tissue damage by wounding or pathogenic infections. Inappropriate migration of tumorigenic cancer stem cells and their progeny in adults also underpins the formation of metastases. Despite this, few mechanistic studies address stem cell migration during repair after injury in adult tissues. Here we present a shielded X-ray irradiation assay that allows us to watch cell migration in the highly regenerative planarian model system. We demonstrate that we can carefully observe migratory behavior and reveal new phenomena concerning migration, not previously observed in planarians. These include observation of cell migration specifically in an anterior direction in the absence of injury. We demonstrate that this homeostatic migration requires the polarity determinant notum. The morphology and distribution of migrating stem cells implicates mechanisms associated with epithelial to mesenchymal transition (EMT). In agreement with this we find that a planarian Snail family transcription factor is necessary for stem cell and stem cell progeny migration to wound sites and for the establishment of migratory morphology. Overall our data establish planarians as a suitable model for further in depth study of cell migration, with the potential to yield novel insights relevant to human biology including hyperplasia during cancer progression. ER -