Drosophila PTPMT1 Has a Function in Tracheal Air-Filling

Summary The fly trachea is the equivalent of the mammalian lung and a useful model for human respiratory diseases. However, little is known about the molecular mechanisms underlying tracheal air-filling during larval development. In this study, we discover that PTPMT1 has a function in tracheal air-filling. PTPMT1 is a widely conserved, ubiquitously expressed mitochondrial phosphatase. To reveal PTPMT1’s functions in genetically tractable invertebrates and whether those functions are tissue-specific, we generate a Drosophila model of PTPMT1 depletion. We find that fly PTPMT1 mutants show impairments in tracheal air-filling and subsequent activation of innate immune responses. On a cellular level, these defects are preceded by aggregation of mitochondria within the tracheal epithelial cells. Our work demonstrates a cell-type specific role for PTPMT1 in fly tracheal epithelial cells to support air-filling and to prevent immune activation. The establishment of this model will facilitate exploration of PTPMT1’s physiological functions in vivo.