The basal transcriptional activity of the murine Klf10 gene is regulated by the transcriptional factor JunB

Background: Krüppel–like factor 10 (KLF10) belongs to the Sp1-like transcription factor family, which plays an important role in many directions, e.g., cell proliferation, apoptosis, and differentiation. Its 5′ upstream regions are conserved across mammalian species. However, the regulatory mechanism has not been elucidated yet. Objective: Nonetheless the basal transcriptional regulation mechanisms of these regions are unknown. Here, we characterized it which is indispensable for the basal transcription of the Klf10 gene. Methods: Seven deletions of 5′ upstream DNA fragments from the 10 kb mKlf10 genomic DNA were produced by PCR and cloned into the upstream of the luciferase (Luc) reporter gene in the pGL3 basic plasmid. Result: The luciferase reporter assay showed that the DNA sequence at positions from −101 to +68 was required for a principle activity in the promoter of mKlf10 gene, in which transcriptional factor binding motifs, one JunB and two Sp1 sites, are included. Mutations at the sequence of JunB motif, but not at the two Sp1, abrogated the promoter activity completely, suggesting the indispensable role of JunB site for basal transcription of mKlf10 gene. Moreover, electrophoretic mobility and supershift assays (EMSA) uncovered that JunB protein bound to this region specifically. Conclusion: Taken together, our study revealed that the JunB but not Sp1 at mKlf10 promoter functions as a positive basic factor for the transcriptional activity of the gene.