TY - JOUR TI - Stretching of the retinal pigment epithelium contributes to zebrafish optic cup morphogenesis AU - Moreno-Mármol, Tania AU - Ledesma-Terrón, Mario AU - Tabanera, Noemi AU - Martin-Bermejo, Maria Jesús AU - Cardozo, Marcos J AU - Cavodeassi, Florencia AU - Bovolenta, Paola A2 - Bronner, Marianne E VL - 10 PY - 2021 DA - 2021/09/21 SP - e63396 C1 - eLife 2021;10:e63396 DO - 10.7554/eLife.63396 UR - https://doi.org/10.7554/eLife.63396 AB - 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. 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 and flatten, thereby matching the retinal curvature and promoting OV folding. Localized interference with the RPE cytoskeleton disrupts tissue 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 drives RPE expansion with a much-reduced need of cell flattening. KW - Zebrafish KW - chick KW - mouse KW - human KW - medaka KW - optic cup KW - morphogenesis KW - tissue tension KW - proliferation KW - squamous epithelium JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -