TY - JOUR T1 - Stretching of the retinal pigment epithelium contributes to zebrafish optic cup morphogenesis JF - bioRxiv DO - 10.1101/2020.09.23.310631 SP - 2020.09.23.310631 AU - Tania Moreno-Mármol AU - Mario Ledesma-Terrón AU - Noemí Tabanera AU - María Jesús Martin-Bermejo AU - Marcos J Cardozo AU - Florencia Cavodeassi AU - Paola Bovolenta Y1 - 2020/01/01 UR - http://biorxiv.org/content/early/2020/09/25/2020.09.23.310631.abstract N2 - The vertebrate eye primordium consists of a pseudostratified neuroepithelium, the optic vesicle (OV), in which cells acquire neural retina or retinal pigment epithelium (RPE) fates. As these fates arise, the OV assumes a cup-shape, influenced by mechanical forces generated within the neural retina. Whether the RPE passively adapts to retinal changes or actively contributes to OV morphogenesis remains unexplored. Here, we generated a zebrafish Tg(E1-bhlhe40:GFP) line to track RPE morphogenesis and interrogate its participation in OV folding. We show that, in virtual absence of proliferation, RPE cells stretch into a squamous configuration, thereby matching the curvature of the underlying retina. Forced proliferation and localized interference with the RPE cytoskeleton disrupt its stretching and OV folding. Thus, extreme RPE flattening and accelerated differentiation are efficient solutions adopted by fast-developing species to enable timely optic cup formation. This mechanism differs in amniotes, in which proliferation largely drives RPE expansion with a much-reduced need of cell flattening.Competing Interest StatementThe authors have declared no competing interest. ER -