Initial Molecular Characterization of Planarian Pigment Cells, a New Model for Studying Lineage Specification and Gut Excretion

ASCs play crucial roles in tissue homeostasis and regeneration. Here, I established pigment cells in Schmidtea mediterranea as a novel model to study ASC lineage specification by identification of hmbs and alas as makers for pigment cells, and ans as a marker for their progenitors. Coexpression analysis between hmbs and tryptophan metabolism enzyme, kmo, suggests ommochrome as one of the responsible pigments for planarian body pigmentation. Initial characterization of this lineage reveals an fst homolog as a negative regulator of pigment cell regeneration and proliferation. Functional studies of light-induced depigmentation also uncover homologs of draper and epimerase as positive regulators of gut excretion mediated pigment cell removal. Together, these findings in pigment cell lineage and gut excretion pave ways to future studies of ASC regulations.