The immunophilin Zonda controls regulated exocytosis in endocrine and exocrine tissues.

Rocío de la Riva-Carrasco, Sebastián Perez-Pandolfo, Sofía Suárez Freire, Nuria M Romero, Zambarlal Bhujabal, Terje Johansen, Pablo Wappner, Mariana Melani

Traffic (Copenhagen, Denmark) 2021 Apr

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Exocytosis is a fundamental process in physiology, that ensures communication between cells, organs and even organisms. Hormones, neuropeptides and antibodies, among other cargoes are packed in exocytic vesicles that need to reach and fuse with the plasma membrane to release their content to the extracellular milieu. Hundreds of proteins participate in this process and several others in its regulation. We report here a novel component of the exocytic machinery, the Drosophila transmembrane immunophilin Zonda (Zda), previously found to participate in autophagy. Zda is highly expressed in secretory tissues, and regulates exocytosis in at least three of them: the ring gland, insulin-producing cells and the salivary gland. Using the salivary gland as a model system, we found that Zda is required at final steps of the exocytic process for fusion of secretory granules to the plasma membrane. In a genetic screen we identified the small GTPase RalA as a crucial regulator of secretory granule exocytosis that is required, similarly to Zda, for fusion between the secretory granule and the plasma membrane. © 2020 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Citation

Rocío de la Riva-Carrasco, Sebastián Perez-Pandolfo, Sofía Suárez Freire, Nuria M Romero, Zambarlal Bhujabal, Terje Johansen, Pablo Wappner, Mariana Melani. The immunophilin Zonda controls regulated exocytosis in endocrine and exocrine tissues. Traffic (Copenhagen, Denmark). 2021 Apr;22(4):111-122