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.