Generation of motoneuron, interneuron and glial cell fates
A long-term interest of the lab has been to understand how neural diversity is generated. A graduate student in the lab, Joanne Odden, is investigating how specific types of motoneurons are produced. Her initial work has been on the Drosophila homologue of homeodomain transcription factor HB9/MNR2. Drosophila HB9 is expressed in a subset of motoneurons that project to the lateral body wall muscles; these are distinct from the pool of Eve+ motoneurons that project to dorsal body wall muscles and from a small pool of motoneurons that project to the ventral-most muscles. RNAi and misexpression experiments are consistent with a model that HB9 is necessary and sufficient for motoneuron targeting to lateral muscles. Additional studies on other transcription factors expressed in some or all motoneurons are ongoing.
A postdoctoral fellow in the lab, Marc Freeman, has done a comprehensive analysis of glial development. Marc is using a novel computational method, microarray technology, and saturation mutagenesis to identify new genes involved in glial development. The computational method identifies putative target genes for the glial cells missing transcription factor, a "master regulator" of glial development. The microarray method looks for genes upregulated following Gcm overexpression in the CNS. These two approaches have already given us over 80 new genes that are involved in glial specification, migration, differentiation, or function. Most of these genes have murine or human orthologs, so it will be interesting to see if they play similar roles in Drosophila and vertebrate gliogenesis.