vrille is required to ensure tracheal integrity in Drosophila embryo

The Drosophila bZIP transcription factor Vrille (VRI) is required for growth, circadian clock regulation and metamorphosis. We identified here a new facet of vrille (vri) function and show that it is required for tracheal development. We show that, in the embryo, VRI is expressed in a complex and dynamic pattern and is found in amnioserosa, subdomains of the developing gut and in trachea cells. We also show that, as expected, the protein is nuclear. We then asked whether VRI was involved in morphogenetic processes such as gut and tracheal development. We therefore investigated the development of these tissues in vri mutants, and although we did not observe any defects in gut morphology, we identified differentiation defects that affect tracheal integrity. Most of the defects were observed after stage 14 and affect all branches, resulting in branch breaks, abnormal branching and elongation.