Interferon Regulatory Factor 6 Determines Epithelial Cell Development and Immunity 1

Intestinal epithelial cells (IECs) form a primary barrier against microbial invasion. Prior studies of enteric pathogens have indicated that IEC defense mechanisms are distinct from those of other cell types. For example, antiviral defense of IECs depends on type III interferon whereas most cell types depend on type I IFN. Interferon regulatory factors (IRFs) are a family of transcription factors with well-described roles in stimulation of IFN cytokines, but IRF6 is unique in its preferential expression by epithelial lineages. IRF6 has primarily been studied in epidermal development, but has relatively unknown roles in the intestinal epithelium. Here, we found that Irf6 KO regulated IFN-stimulated antiviral immunity of IECs but had no effect on macrophages. RNseq analysis of Irf6 KO cells showed significant differences in the IFN-stimulated gene expression program that correlated with the magnitude of antiviral gene stimulation. We also found significant baseline phenotypic and transcriptional changes in Irf6 KO IECs, with reduced rate of growth and preturbation of growth and differentiation pathway genes. Knockout of Irf6 in primary IEC organoids also resulted in slower growth and smaller size. Transcriptional analysis of Irf6 KO organoids indicated reduced expression of genes in the epithelial differentiation pathwya, including Wnt and Notch pathway genes, as well as increased expression of a subset of IFN-stimulated genes. These data indicate a previously unappreciated role of Irf6 in shaping the IEC transcriptome, including baseline epithelial development genes and IFN-stimulated genes. Overall design: Mouse IEC cell lines (derived from M2C cells, Padilla-Nash et al., 2012; doi: 10.1002/gcc.21921) were transduced with lentivirus encoding Cas9 and gRNA against Irf6 or non-targeting control, and monoclonal isolates were sequence-confirmed for disruption of the Irf6 locus. Treatments were added to cultured cells, and RNA was isolated twenty-four hours after treatments. Samples were collected in experimental triplicate.