PT  - JOURNAL ARTICLE
AU  - Maria Marsal
AU  - Amayra Hernández-Vega
AU  - Philippe-Alexandre Pouille
AU  - Enrique Martin-Blanco
TI  - Rab5-mediated Yolk Cell Endocytosis modulates Zebrafish Epiboly Biomechanics and Tissue Movements
AID  - 10.1101/097212
DP  - 2017 Jan 01
TA  - bioRxiv
PG  - 097212
4099  - http://biorxiv.org/content/early/2017/01/20/097212.short
4100  - http://biorxiv.org/content/early/2017/01/20/097212.full
AB  - Morphogenesis in early embryos demands the coordinated distribution of cells and tissues to their final destination in a spatio-temporal controlled way. Topographical and scalar differences in adhesion and contractility are essential for these morphogenetic movements, while the role that membrane remodeling may play remains less clear. To determine how surface turnover may modulate tissue arrangements during embryogenesis we studied epiboly in the zebrafish. Experimental analyses and modeling have shown that the expansion of the blastoderm during epiboly relies on an asymmetry of mechanical tension along the embryo surface. In this scenario, we found that membrane turnover at the external yolk cell syncytial layer (E-YSL) in early zebrafish embryos is mainly directed by the GTPase Rab5ab. Rab5ab was essential for endocytosis, and interference in its expression resulted in reduction of yolk cell actomyosin contractility, disruption of cortical and internal flows, a disequilibrium in force balance and epiboly impairment. We conclude that regulated membrane remodeling is crucial for directing cell and tissue mechanics and coordinating morphogenetic movements.