Figure 6. Balance between endocytosis and recycling modulates cellular morphology.

(A-C) Confocal sections from Drosophila embryos expressing Rab5^DN and Rab11^DN simultaneously in the AS immunostained with an anti-DE-Cadherin antibody, showing cell shapes similar to the wild types. Still images from a time-lapse video of an embryo co-expressing Rab5^DN and Rab11^DN in the AS (D) and ubi-DE-CadherinGFP at indicated stages after the start of DC (Movie S8). (E) Measurement of the distance between the two opposing epithelia in these embryos. (F) Quantification of apical surface area, cell anisotropy and membrane content of 5 cells of 1 embryo over time. This embryo show features more similar to the wild type for the parameters analyzed, however zippering is defective and DC fails (D-240’). (G) Automated analysis of apical cell areas at the beginning of DC, as shown in Figure 5E–F. We found two different types of AS > [Rab11^DN + Rab5^DN] embryos. In G1, an example embryo is depicted in which values for cell areas, direction of elongation and gradient of cell areas are close to wild type embryos. In G2 type embryos cells are smaller, the gradient is not as defined and cell elongation is random. The proportion of cells in each of the cell area classes is very similar to wild type (G3). (H) Model of the balance between endocytosis and recycling in cell morphology. When Rab5 mediated endocytosis is blocked there is less removal of membrane, which results in more membrane in AS cells and when Rab11 function is impaired, the insertion of membrane through Rab11 endosomes is blocked, and the apical membrane content is reduced.