Application of Zebrafish and Knockdown Technology to Define Progranulin Neuronal Function

The zebrafish (Danio rerio), a small tropical fish, has become a powerful model for the study of early vertebrate development, human diseases, and drug screening. Zebrafish provides large numbers of optically clear embryos, and its development is very rapid. Overexpression or under-expression of proteins can be effectively achieved by microinjection of mRNA or morpholino antisense oligonucleotides (MOs), respectively, into developing embryos at the 1-2 cell stage. The function of a particular protein can be revealed by correlating gene expression patterns with the phenotypes observed from over- or under-expression. We defined the expression pattern of zebrafish progranulin A (zfPGRN-A), an orthologue to the single human PGRN by whole-mount in situ hybridization (ISH) and immunofluorescence (IF). The MO-mediated knockdown of zfPGRN-A expression generated embryos that display abnormal motor neuron development resulting in touch-evoked swimming deficits.