The Exocytic Pathway and Development
Hans Schotman and Catherine Rabouille
The development of a multicellular organism is mostly controlled at the transcriptional level but it has also been shown to require the transport of membrane and proteins through the exocytic pathway to the plasma membrane and the extracellular medium. As they are transported in the different compartments making up this pathway, newly synthesized proteins are modified and dispatched to their final destinations. In this review, we will first outline how mutations in genes encoding key proteins of this pathway, such as components of the COPII coat, tethers, components of the SNARE machinery, glycosylation enzymes, etc, lead to severe developmental defects. In the second part, we will describe how specific steps of epithelial development, such as epithelial cell formation, establishment of polarity, junction formation and morphogen secretion, are controlled or regulated by the exocytic machinery.