Identification of Klf9-regulated genes in HT22 tissue culture cells [RNA-Seq]

Krueppel-like factor 9 (Klf9) is a DNA-binding transcription factor that has been implicated in neuronal development and regeneration. We used mouse hippocampus-derived HT22 cell line to identify genes differentially regulated by forced Klf9 expression. We stably transfected HT22 cells with pCDNA6:TR (encoding the Tet repressor) and pCDNA6:TO-Klf9 (encoding Klf9 downstream of the Tet operator), allowing doxycycline(dox)-inducible expression of Klf9. We chose a stably transfected clone with baseline Klf9 mRNA level similar to that of untransfected HT22 cells (parent line) and approximately 10-fold induction after dox treatment. We conducted RNA-seq on stably transfected HT22 cells treated with or without dox for 8 hours; we also conducted RNA-seq on parent cells subjected to the same dox treatment to separate nonspecific effects of dox from the effects of forced Klf9 expression. Analysis of RNA-seq data found 217 gene repressed and 21 upregulated by forced Klf9 expression (FDR-adjusted p<.005; because fold changes were small we used a stringent p value cutoff to ensure that we were studying genes likely to be bona fide targets), showing that Klf9 functions primarily as a transcriptional repressor. Gene ontology analysis showed that Klf9-repressed genes were enriched in cytoskeletal and Wnt signaling-related genes.