Oxygen regulation of airway branching in Drosophila is mediated by branchless FGF.
The Drosophila tracheal (respiratory) system is a tubular epithelial network that delivers oxygen to internal tissues. Sprouting of the major tracheal branches is stereotyped and controlled by hard-wired developmental cues. Here we show that ramification of the fine terminal branches is variable and regulated by oxygen, and that this process is controlled by a local signal or signals produced by oxygen-starved cells. We provide evidence that the critical signal is Branchless (Bnl) FGF, the same growth factor that patterns the major branches during embryogenesis. During larval life, oxygen deprivation stimulates expression of Bnl, and the secreted growth factor functions as a chemoattractant that guides new terminal branches to the expressing cells. Thus, a single growth factor is reiteratively used to pattern each level of airway branching, and the change in branch patterning results from a switch from developmental to physiological control of its expression.
Jarecki
J
J
Howard Hughes Medical Institute, Department of Biochemistry, Stanford University School of Medicine, California 94305-5307, USA.
Johnson
E
E
Krasnow
M A
MA
D000818:Animals; D030801:Animals, Genetically Modified; D003463:Cues; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000033:anatomy & histology / Q000235:genetics / Q000502:physiology*; D005346:Fibroblast Growth Factors / Q000235:genetics / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D019476:Insect Proteins / Q000235:genetics / Q000502:physiology*; D007814:Larva; D008565:Membrane Proteins / Q000235:genetics / Q000502:physiology; D009030:Mosaicism; D016296:Mutagenesis; D010100:Oxygen / Q000502:physiology*; D050683:R-SNARE Proteins; D020545:Respiratory Mucosa / Q000033:anatomy & histology / Q000502:physiology*; D012143:Respiratory Physiological Phenomena; D012137:Respiratory System / Q000033:anatomy & histology
D029721:Drosophila Proteins; D019476:Insect Proteins; D008565:Membrane Proteins; D050683:R-SNARE Proteins; C102644:bnl protein, Drosophila; D005346:Fibroblast Growth Factors; D010100:Oxygen