Rhomboid 3 orchestrates Slit-independent repulsion of tracheal branches at the CNS midline

• DOI: 10.1242/dev.01242
• Publication Date: 2004-07-01T01:47:15Z
• Authors: Marco Gallio; Camilla Englund; Per Kylsten; Christos Samakovlis
• Keywords: Central Nervous System; 0301 basic medicine; Epidermal Growth Factor; Serine Endopeptidases; Membrane Proteins; Nerve Tissue Proteins; ErbB Receptors; Proto-Oncogene Proteins c-raf; Repressor Proteins; Trachea; 03 medical and health sciences; Drosophila melanogaster; Morphogenesis; ras Proteins; Animals; Drosophila Proteins; Eye Proteins; In Situ Hybridization; Body Patterning; Signal Transduction

EGF-receptor ligands act as chemoattractants for migrating epithelial cells during organogenesis and wound healing. We present evidence that Rhomboid 3/EGF signalling, which originates from the midline of the Drosophilaventral nerve cord, repels tracheal ganglionic branches and prevents them from crossing it. rho3 acts independently from the main midline repellent Slit, and originates from a different sub-population of midline cells: the VUM neurons. Expression of dominant-negative Egfr or Ras induces midline crosses,whereas activation of the Egfr or Ras in the leading cell of the ganglionic branch can induce premature turns away from the midline. This suggests that the level of Egfr intracellular signalling, rather than the asymmetric activation of the receptor on the cell surface, is an important determinant in ganglionic branch repulsion. We propose that Egfr activation provides a necessary switch for the interpretation of a yet unknown repellent function of the midline.