Control of tube diameter expansion by secreted chitin-binding proteins
(English)Manuscript (preprint) (Other academic)
The size and shape of epithelial tubes determine the transporting capacities of tubular organs. Here, we analyze two genes involved in airway tube size regulation in Drosophila. Obst-A and gasp encode secreted proteins with chitin binding domains that are conserved among insect species. mRNA in situ hybridizations show that both genes are strongly expressed during airway tube expansion. Gasp protein is secreted into the airway tubes and colocalizes with a chitin binding probe and other chitin binding proteins. Analysis of obst-A and gasp single mutants and obst-A; gasp double mutant shows that both genes are required for larval elongation and airway tube dilation. The assembly of the apical chitinous matrix of the airway tubes is defective in gasp and Obst-A mutants. The defects become exaggerated in double mutants indicating that the genes have partially redundant functions in chitin structure modification. The phenotypes in luminal chitin assembly in the airway tubes are accompanied with a corresponding reduction of tube diameter in the mutants. Conversely, overexpression of Obst-A or Gasp in the airways expands the tube circumference. Our results indicate that the level of distinct matrix binding proteins in the tubes determines the extent of diametric growth. We propose that Obst-A and Gasp organize the assembly of the luminal matrix and thereby provide distending forces that stretch the apical cell membranes to expand tube diameter accordingly.
Research subject Developmental Biology
IdentifiersURN: urn:nbn:se:su:diva-62417OAI: oai:DiVA.org:su-62417DiVA: diva2:441690