THE SPATIAL-TEMPORAL EXPRESSION PATTERNS OF SMALL MAF AND THEIR EFFECTS ON THE REGULATION OF ZYMOGENS IN ZEBRAFISH

The members of musculoaponeurotic fibrosarcoma oncogene (Maf) family are important transcription factors that are involved in many cascades of cell biology. They are classified into large and small Maf proteins. The small Maf proteins of zebrafish include Mafk, Mafg1, Mafg2 and Maff (Maft). Mafg1 and mafg2 are paraloges of mafg that only exist in fish genomes. The phylogenetic tree indicated that the evolution of the small Mafs was conservative. The systemic analyses of different small mafs also showed that mafk and maff were more conservative than mafg. In the present study we analyzed the spatial-temporal expression of these four mafs in the early development of zebrafish embryos using semiquantitative PCR and whole mount in situ hybridization. The expression of all four genes started at the one cell stage, suggesting that these genes were maternal and the expression were ubiquitous in early zebrafish embryos. Mafg2 showed the highest expression level among the four genes, and was specifically expressed in blood circulation after 48 hpf, together with maff. The results of dual-luciferase system also showed that the over expression of the four small Mafs led to down-regulation of the transcription of zymogens in a dose-dependent manner. Our study should contribute to better understanding of the functional superposition and complementarities of small Mafs.