Gcm specifies glia (red), but the glial subset NGB1-1A requires higher Gcm levels (top).
GIANGRANDE/EMBO
Neuron subtypes are specified through diversity: each subtype gets its own transcription factor. But in the lateral glia of
Drosophila, specification of all glial cell types is controlled by a single fate-determining gene called
Glide/Gcm (
gcm). How can just one gene make many glial cell types? Rossana De Iaco, Angela Giangrande (National Center for Scientific Research in Strasbourg, France), and colleagues provide the solution for one type of glial cell. They show that although low expression of the
gcm gene make cells competent to become glia, a boost in expression level regulates the type of glia that cells will become.
Glia fail to form in mutant embryos lacking gcm. In mutants lacking a patterning protein called Huckebein (Hkb), one type of glia—the product of one specific...
