Regulation of secretion
Modulation of secretion during development
Secretion at the Hubrecht
Secretion is mediated by the secretory pathway that has the same basic functional organisation in Drosophila as in mammalian cells.
Proteins destined to the plasma membrane or the extracellular medium are classically transported through the secretory pathway (ER>ERES>Golgi>PM). However, secretion can be modulated by development and physiology.
- First, classical secretion switches to unconventional secretion (Golgi bypass) in several re-arranging Drosophila epithelium for the delivery of a number of adhesion and junctional proteins. Strikingly, this is mediated by the upregulation of the dgrasp gene that encodes the Golgi protein dGRASP. Whether this pathway also exists in mammals remains to be fully investigated.
- Second, secretion can also be modulated by physiological conditions. We show that under amino-acid starvation in the Drosophila S2 cells, the key tER protein ERES Sec16 is phosphorylated at its C-terminus, leading to its release from the ER exit sites and secretion inhibition. Surprisingly, this is not mediated through TORC1 but through the unconventional MAPK, ERK7. These results suggest that inhibition of secretion in the absence of nutrient is an active mechanism, not only a passive response to the absence of growth factors via ERK2.
We can share expertise and offer help with fluorescent and immune-electron microscopy to visualize:
- Compartments and markers along the secretory pathway in Drosophila S2 cells and Drosophila tissue.
- RNA FISH and ISH-IEM in tissues
- Live cell imaging