Glide2, a second glial promoting factor in Drosophila melanogaster

The fly glial cell deficient/glial cell missing (glide/gcm) gene codes for a transcription factor that induces gliogenesis. Lack of its product eliminates lateral glial cells in the embryonic nervous system. Here we identify a second gene, glide2, that is homologous to glide/gcm in the binding domain and that is also necessary and sufficient to promote glial differentiation. glide2 codes for a transcription factor that displays a weaker and delayed expression compared with glide/gcm. The two genes, which are located 27 kb apart and share cis-regulatory elements, are able to auto- and cross-regulate, indicating that they form a gene complex. Finally, we show that lack of both products eliminates all lateral glial cells, which means that the two genes contain all the fly lateral glial promoting activity.