Identification of Klf9 genomic binding sites in HT22 tissue culture cells [ChIP-Seq]

Krueppel-like factor 9 (Klf9) is a DNA-binding transcription factor that has been implicated in neuronal development and regeneration, but none of its genomic targets are known in neurons. We used the mouse hippocampus-derived cell line HT22 to identify Klf9’s genomic binding sites in neurons. We stably transfected HT22 cells with the biotin ligase BirA with or without co-transfection of a Klf9 fusion protein with an n-terminal FLAG tag and a biotin ligase recognition peptide. This allowed us to precipitate Klf9 in chromatin using streptavidin. This permits the use of more stringent wash conditions, improving signal-to-noise ratio. We conducted high-throughput sequencing on DNA precipitated from these lines and identified 3,378 regions where Klf9 associated in chromatin. We found that Klf9 associated near transcription start sites and that its genomic targets were enriched for genes related to cytoskeletal regulation and apoptosis.