Zonda: an ER inmmunophilin that regulates protein secretion

PABLO WAPPNER; ROCIO VICTORIA DE LA RIVA CARRASCO; MARIANA MELANI; SEBASTIAN PÉREZ PANDOLFO

Conferencia; Buenos Aires Reseach Conference on Autophagy; 2017

An increasing body of evidence supports the notion that intra-vesicular trafficking pathways are closely interconnected. In particular, several autophagy genes have been associated with secretory pathways and vice versa. Drosophila melanogaster larval salivary glands are a powerful genetic model for studying the secretory pathway; they synthesize and secrete Glue proteins ? a family of mucins- during the last larval stage in response to hormone stimulation. We have recently characterized the autophagic function of a novel Drosophila gene that we named zonda, an immunophilin that localizes at the ER, and asked if Zonda participates in glue granule secretion. We found that Zonda knock-down cells retain glue protein in large secretory granules. In wild type cells mature glue granules make contact with the plasma membrane resulting in the incorporation to the secretory granule of plasma membrane components, and posterior recruitment of filamentous actin cytoskeleton around the glue granule necessary for content release. We found that in Zonda mutant cells, the contact of glue granules with the plasma membrane is impaired, affecting the formation of the actin coat around the granules. These results suggest a role for Zonda in glue granule secretion, potentially involving the tethering of mature granules to the plasma membrane.