Klf4 could be activated by Pou5f3/Stat3 to induce the expression of Nanog in Japanese flounder.

Abstract Krüppel-like factor 4 (Klf4) is a zinc finger protein transcription factor of the KLF family and plays an important role in various important biological process, including cell proliferation, differentiation, embryonic development, and cancer formation. In this study, the full length Klf4 cDNA sequence of Japanese flounder (Paralichthys olivaceus) was analyzed. Phylogenetic, gene structure, and synteny analysis revealed that PoKlf4 was conserved to that of teleost. Transcript of PoKlf4 showed that its expression was high during early embryonic development but reduced when gastrulation began, thus indicating its possible role in embryonic development. Tissue expression pattern showed that PoKlf4 was expressed higher in ovaries than in testes. ISH revealed that PoKlf4 was also expressed in spermatogonium, oocytes, and oogonia and in high levels in epithelial and lamellar epithelial cells of gills. Functional characterization of PoKlf4 gene promoter provided valuable information in understanding the molecular regulatory mechanisms of PoKlf4 gene. PoKlf4 could up-regulate Nanog , a gene that prevents ES cells from differentiating and being up-regulated by Pou5f3 and Stat3 genes that could maintain ES cell self-renewal. These results suggested that PoKlf4 maintains the pluripotency of ES cells. This study provides valuable information in exploring the regulatory network of PoKlf4 and lays the foundation for further research on the function of this gene. Highlights • The cDNA of Klf4 gene was isolated and characterized from Japanese flounder. • The expression profiles of Klf4 were analyzed by qRT-PCR and ISH. • PoKlf4 could up-regulate Nanog , and PoKlf4 was regulated by Pou5f3 and Stat3. [ABSTRACT FROM AUTHOR]