Transcytosis via the late endocytic pathway as a cell morphogenetic mechanism.

Renjith Mathew,L Daniel Rios‐Barrera,Maria Leptin,Pedro Machado,Yannick Schwab

doi:10.15252/embj.2020105332

Renjith Mathew, L Daniel Rios‐Barrera + Show 3 more

Open Access

https://doi.org/10.15252/embj.2020105332

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Abstract

Plasma membranes fulfil many physiological functions. In polarized cells, different membrane compartments take on specialized roles, each being allocated correct amounts of membrane. The Drosophila tracheal system, an established tubulogenesis model, contains branched terminal cells with subcellular tubes formed by apical plasma membrane invagination. We show that apical endocytosis and late endosome‐mediated trafficking are required for membrane allocation to the apical and basal membrane domains. Basal plasma membrane growth stops if endocytosis is blocked, whereas the apical membrane grows excessively. Plasma membrane is initially delivered apically and then continuously endocytosed, together with apical and basal cargo. We describe an organelle carrying markers of late endosomes and multivesicular bodies (MVBs) that is abolished by inhibiting endocytosis and which we suggest acts as transit station for membrane destined to be redistributed both apically and basally. This is based on the observation that disrupting MVB formation prevents growth of both compartments.

Highlights

Most cells have specialized plasma membrane domains that serve dedicated physiological purposes
90 Results Organization of membrane domains during subcellular tube morphogenesis Tracheal terminal cells elongate with their subcellular tube and outer membrane compartment growing at the same rate (Fig. 1A-D)
They were seen with other general membrane reporters (Fig. S1A-C), but not with markers considered to be selective for the plasma membrane, such as the Pleckstrin homology domain (PH) of PLCδ fused to GFP or mCherry

Summary

Introduction

Most cells have specialized plasma membrane domains that serve dedicated physiological purposes. Epithelial cells have an apical and a basal domain separated by adherens junctions and facing different parts of the body. Membrane and proteins are allocated to these domains in a way that is commensurate with their functions. Absorptive epithelia have massively enlarged apical domains organized in microvilli, and photoreceptor cells form specialized membranous outer segments for the light-sensing rhodopsins.

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