Investigation of Irx3/5 and Plzf Hidden Functions through Comparison of Allelic Series and Analysis of Genetic Markers
More than 150 genes and regulatory regions are identified to be involved in the onset of congenital limb malformation. Of which, the gene complex Irx3/5 and gene Plzf are studied recently via knockout analysis in mice, which showed different defects in the proximal-anterior aspect of hindlimb when each gene is singularly knocked out. This commonality leads to the hypothesis that Irx3/5 and Plzf exhibit redundant function in the regulation of mammalian hindlimb development, which was studied through both phenotypic and genotypic analysis of the Irx3/5 and Plzf allelic series. The phenotypic analysis of E14.5 allelic series embryos showed similarities between Plzf KO and Irx3/5+/-;Plzf KO, as well as Irx3/5 dKO and Irx3/5 dKO;Plzf+/-, but a total loss of hindlimb in Irx3/5;Plzf tKO that was not observed in any other genotype of the series. Genotypic analysis of E10.5 and E11.5 stages found that hindlimb bud was actually present in these earlier stages, and that Gli1 expression deviates in mutants. The analysis found evidence for gene interaction upon the observation of total loss of hindlimb in tKO, as well as further indication of sonic hedgehog (Shh) signaling pathway in the hindlimb development process, as Shh gives rise to Gli1.