CONTROL OF MIDLINE GLIA DEVELOPMENT IN THE EMBRYONIC DROSOPHILA CNS

The midline glial cells are required for correct formation of the axon al pattern in the embryonic ventral nerve cord of Drosophila. Initiall y, six midline cells form an equivalence group with the capacity to de velop as glial cells. By the end of embryonic development three to fou r cells are singled out as midline glial cells. Midline glia developme nt occurs in two steps, both of which depend on the activation of the Drosophila EGF-receptor homolog and subsequent ras//raf-mediated signa l transduction. Nuclear targets of this signalling cascade are the ETS domain transcription factors pointedP2 and yan. In the midline glia p ointedP2 in turn activates the transcription of argos, which encodes a diffusible negative regulator of EGF-receptor signalling. (C) 1997 El sevier Science Ireland Ltd.