title: Positive autoregulation of the glial promoting factor glide/gcm.
abstract: Fly gliogenesis depends on the glial-cell-deficient/glial-cell-missing (glide/gcm) transcription factor. glide/gcm expression is necessary and sufficient to induce the glial fate within and outside the nervous system, indicating that the activity of this gene must be tightly regulated. The current model is that glide/gcm activates the glial fate by inducing the expression of glial-specific genes that are required to maintain such a fate. Previous observations on the null glide/gcmN7-4 allele evoked the possibility that another role of glide/gcm might be to maintain and/or amplify its own expression. Here we show that glide/gcm does positively autoregulate in vitro and in vivo, and that the glide/gcmN7-4 protein is not able to do so. We thereby provide the first direct evidence of both a target and a regulator of glide/gcm. Our data also demonstrate that glide/gcm transcription is regulated at two distinct steps: initiation, which is glide/gcm-independent, and maintenance, which requires glide/gcm. Interestingly, we have found that autoregulation requires the activity of additional cell-specific cofactors. The present results suggest transcriptional autoregulation is a mechanism for glial fate induction.
authors.affiliation: Institut de Génétique et Biologie Moléculaire et Cellulaire, IGBMC/CNRS/INSERM/ULP, BP 163 67404 Illkirch, Communauté Urbaine de Strasbourg, France.
authors.forename: A A
authors.initials: AA
authors.lastname: Miller
authors.forename: R
authors.initials: R
authors.lastname: Bernardoni
authors.forename: A
authors.initials: A
authors.lastname: Giangrande
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D002454:Cell Differentiation / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics; D004330:Drosophila / Q000196:embryology / Q000235:genetics*; D018507:Gene Expression Regulation, Developmental / Q000235:genetics*; D020904:Glia Maturation Factor; D007150:Immunohistochemistry; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000235:genetics*; D009457:Neuroglia / Q000166:cytology; D017354:Point Mutation / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics; D015533:Transcriptional Activation / Q000235:genetics
chemical_list: D004268:DNA-Binding Proteins; D020904:Glia Maturation Factor; D009419:Nerve Tissue Proteins; D014157:Transcription Factors