Temporal Expression of Transcription Factors Runx2 and Osterix During Early Development of Cynoglossus semilaevis

Abstract:

Transcription factors Runx2 and Osterix play a vital role in the formation and differentiation of the skeleton in mammals. To date, there have been few reports on the regulatory mechanisms of the skeleton development in fish. In this study, we cloned the cDNA sequences of Runx2 and Osterix in Cynoglossus semilaevis, and examined their expression patterns in 13 tissues of both female and male adults using qRT-PCR. The results showed that Runx2 and Osterix mRNA were highly expressed in spleen, and moderately expressed in dorsal fin and brain. Next we detected and measured the levels of Runx2 and Osterix mRNA at early developmental stages including the egg, larva, juvenile and fingerling stages. The temporal expression patterns are: 1) the mRNA level of Osterix was always significantly higher than Runx2 during all developmental stages in this study; 2) at stages prior to hatching, the highest level of Runx2 was observed in the cleavage and gastrula stages and then it dropped to a very low level, and the Osterix mRNA level increased and reached the peak in the embryonic stage; 3) at early larvae stages (1−5 days old), the expression of both Runx2 and Osterix first increased followed by a decline; 4) as for the 10−90 day-old fish, there was no variation in the expression pattern of Runx2 or Osterix mRNA. These results suggested that Runx2 and Osterix could participate in the regulation of early development in C. semilaevis. However, further studies are needed to explore their roles in the skeleton development.