Characterization and Spatiotemporal Expression of Klf4 in Large Yellow Croaker Larimichthys crocea

As one of transcription factors and pluripotency factors, Klf4 plays a crucial role in regulation of cellular processes. In this article, we characterized Klf4 of large yellow croaker (Lc-Klf4), which encodes a 452-amino acid protein (LcKlf4) with three highly conserved C2H2 zinc fingers. Lc-Klf4 shares high conservative functions in teleosts with the closest relationship with Stegastes partitus. The spatiotemporal expression showed that Lc-Klf4 was expressed widely in adult tissues with gender difference as follows: brain> gill> eye> heart in female; heart> testis> gill> brain in male; male> female in heart, gill, and testis; and female> male in eye. During growth, the highest expression level of Lc-Klf4 was at 635 dph (days posthatching) in testis and at 270 dph and 635 dph in brain. Besides, Lc-Klf4 was widely and highly distributed in different developmental spermatids especially in spermatocytes. The expression of Lc-Klf4 in embryos was exhibited zygotically beginning from late gastrula stage with high level in closure of blastopore stage and appearance of optic vesicle stage. This expression pattern was supported by whole-mount in situ hybridization with high expression in back and head of late embryos. In conclusion, the spatiotemporal expression patterns of LcKlf4 illustrated that Klf4 involves in spermatogenesis, embryogenesis, and adult physiological processes.