Studies of conserved cell-cell signaling pathways in the planarian, schmidtea mediterranea

The incredible ability of planarian flatworms to regenerate from almost any type of injury has fascinated naturalists for centuries. Clearly, well-coordinated means of cellcell communication must be critical for this process to occur. This dissertation interrogated the roles of three conserved cell-cell signaling pathways during planarian regeneration: the Wnt, Hedgehog, and Notch pathways. Specifically, the Wnt pathway offered critical insights into discrete phases of the planarian wounding response and axial patterning. The Hh pathway was found to be involved in specification of the anteriorposterior axis, and its function is independent of cilia. Finally, the Notch pathway had numerous roles in planarians, including generation of cellular diversity in the mucociliary epidermis, regeneration of various sensory organs, and maintenance of midline identity. Cumulatively, we hope that this work serves as a useful foundation for future studies of the complex cell-cell signaling events underpinning the amazing regeneration biology of planarian flatworms.