KLF7 Promotes Preadipocyte Proliferation via Activation of the Akt Signaling Pathway by Cis-regulating CDKN3

Kruppel-like transcription factor 7 (KLF7) promotes preadipocyte proliferation; however, its target gene in this process has not yet been identified. Using KLF7 ChIP-seq analysis, we previously showed that a KLF7-binding peak is present upstream of the cyclin-dependent kinase inhibitor 3 gene (CDKN3) in chicken preadipocytes. In the current study, we identified CDKN3 as a target gene of KLF7 that mediates the effects of KLF7 on preadipocyte proliferation. Furthermore, 5'-truncating mutation analysis showed that the minimal promoter was located between CDKN3 nt -160 and nt -7 (relative to the translation initiation codon ATG). KLF7 overexpression increased CDKN3 promoter activity in the DF-1 and immortalized chicken preadipocyte (ICP1) cell lines. Deletion of the putative binding site of KLF7 abolished the promotive effect of KLF7 overexpression on CDKN3 promoter activity. Moreover, CDKN3-knockdown and -overexpression assays revealed that CDKN3 enhanced ICP1 cell proliferation. Flow cytometry analysis showed that CDKN3 accelerated the G1/S transition. Further, we found that KLF7 promoted ICP1 cell proliferation via Akt phosphorylation by regulating CDKN3. Taken together, these results suggest that KLF7 promotes preadipocyte proliferation via activating the Akt signaling pathway by cis-regulating CDKN3, thus driving the G1/S transition.