The neural crest is a transient population of cells that forms a diverse range of derivatives in vertebrate embryos. Neural crest cells also migrate extensively throughout the embryo. The specification of a number of neural crest derivatives, including pigment cells and neurons and glia of the peripheral nervous system, is dependent on the transcription factor Sox10. In sox10 mutant zebrafish embryos, these neural crest derivatives fail to specify and subsequently the cell differentiation and migration fails leading to apoptosis. Sox10 mutant embryos also display an ear defect although the precise role of Sox10 in the ear is less well defined. Thus Sox10 controls an extensive gene regulatory network that drives the development of an important subset of neural crest derivatives and also functions during ear development. This gene regulatory network is currently poorly defined.
The aim of this project was to identify genes that are both direct and indirect targets of Sox10 to further elucidate this gene regulatory network. To achieve this, a microarray approach was adopted. Initially, fluorescence activated cell sorting was employed to enrich for sox10 expressing cells from 24 hours post fertilization sox10:GFP transgenic embryos. The transcriptomes of WT and sox10 mutant cells were compared by microarray analysis to identify differentially regulated genes. A large number of target genes were identified by this method and by an unbiased in situ hybridization screen, 28 genes were validated. Of these, 23 genes were expressed in cells of the neural crest and down-regulated in sox10 mutant embryos. The majority of these genes were expressed in cells of the melanocyte and xanthophore lineages. 5 genes were expressed in the ear (otic vesicle) of which three otic vesicle genes were down-regulated while two otic vesicle genes were up-regulated in sox10 mutant embryos. Unfortunately due to time constraints, a study into the function of one of these target genes could not be completed.
The series of validated genes identified during this project has opened new opportunities for research and has identified a number of highly expressed marker genes that will be useful in future studies. In addition, the microarray data presented will be a useful resource to aid the identification of further targets of Sox10.
|Date of Award
|1 Aug 2009
|Robert Kelsh (Supervisor)
- Waardenburg-Shah syndrome