Characterization of the Hoxd4 neural enhancer
Ler, Ser Yeng
Date of Issue2012
School of Biological Sciences
Hox genes encode homeodomain-containing transcription factors, required for correct antero-posterior patterning. In mammals, there are 39 Hox genes, distributed over four clusters, named A-D, and they are subdivided into thirteen paralogs. The main project objective is to understand Hox gene regulation through the study of Hoxd4 neural enhancer(s). Hoxd4 is the fourth paralog in the HoxD cluster. It has an anterior expression border between segments (rhombomeres (r)) 6/7 of the developing hindbrain which is governed by the 3’ neural enhancer in mouse embryos. However, my study showed that the zebrafish 5’ neural enhancer was responsible for this function in zebrafish embryos. Evolutionarily conserved sites in the 3’ neural enhancer are important to its activity. Genetic evidence suggests that the Maf family transcription factor, Kreisler (Kr)/MafB represses Hoxd4 expression in the mouse embryonic hindbrain. I demonstrated similar observation with Valentino (Val) in zebrafish embryos.