Research Interest: Pattern formation during central nervous system development My laboratory is addressing the interactions that occur between members of the Hox gene family during embryonic development. Hox genes encode transcription factors that are expressed in broad anteroposterior domains in developing vertebrate embryos. Inactivation of different members of the Hox gene family suggests that these genes are active in embryonic patterning. We have defined the anatomical phenotypes for mice carrying mutations in several individual Hox genes and are currently breeding and analyzing mice carrying multiple mutations. Our studies have demonstrated that motor neuron position and projection is specifically affected by Hox gene mutations both individually and in combination. We are also examining downstream targets of Hox gene activity using microarray screening. We have identified a set of genes that are differentially expressed in the nervous system following mutation of a single Hox gene. Rt-PCR studies have demonstrated that some of these genes show additional changes in expression in double mutant animals, suggesting that several Hox genes may regulate the same downstream target genes. We are currently defining the promoter elements that may be responsible for these gene interactions.