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Glue Secretion in the Drosophila Salivary Gland: A Model for Steroid-Regulated Exocytosis

Summary: Glue Secretion in the Drosophila Salivary Gland:
A Model for Steroid-Regulated Exocytosis
Assel Biyasheva,1
Thuy-Vy Do,1
Yun Lu,
Martina Vaskova, and Andrew J. Andres2
Department of Molecular Pharmacology and Biological Chemistry, Robert H. Lurie
Comprehensive Cancer Center, Northwestern University, Chicago, Illinois 60611-3093
Small hydrophobic hormones like steroids control many tissue-specific physiological responses in higher organisms.
Hormone response is characterized by changes in gene expression, but the molecular details connecting target-gene
transcription to the physiology of responding cells remain elusive. The salivary glands of Drosophila provide an ideal model
system to investigate gaps in our knowledge, because exposure to the steroid 20-hydroxyecdysone (20E) leads to a robust
regulated secretion of glue granules after a stereotypical pattern of puffs (activated 20E-regulated genes) forms on the
polytene chromosomes. Here, we describe a convenient bioassay for glue secretion and use it to analyze mutants in
components of the puffing hierarchy. We show that 20E mediates secretion through the EcR/USP receptor, and two
early-gene products, the rbp function of BR-C and the Ca2
-binding protein E63-1, are involved. Furthermore, we
demonstrate that 20E treatment of salivary glands leads to Ca2
elevations by a genomic mechanism and that elevated Ca2
levels are required for ectopically produced E63-1 to drive secretion. The results presented establish a connection between


Source: Andres, Andrew - School of Life Sciences, University of Nevada at Las Vegas


Collections: Biology and Medicine