α stat3 c 20

Mice were injected 1 μg recombinant IL-22 (Peprotech) or PBS i.p. 1h prior to epithelial cell isolation. Epithelial cells were isolated as described above. Cells were resuspended in PBS and fixed with 0.75% paraformaldehyde. Fixation was stopped with glycine and cells were washed and lysed in 50mM Tris, 2.5mM EDTA, 0.1% NP-40 and 10 % Glycerol. Nuclei were lysed in 50mM Tris, 5mM EDTA and 0.25% SDS and subsequently sonicated in a Bioruptor Plus (Diagenode). Lysates were cleared by centrifugation and stored at -80°C. Protein-A-coated magnetic beads (Diagenode) were blocked with yeast tRNA (Life Technologies) and BSA (New England Biolab). Nuclear lysates were split in 10% input and 90% immunoprecipitation solutions. The latter was incubated with α-STAT3 (C-20; Santa Cruz Biotechnology) overnight rotating at 4°C. Protein-A coded magnetic beads were added and incubated for another 30min rotating at 4°C. Beads were purified and washed repeatedly. Bound DNA was eluted in 10mM TRIS, 1 mM EDTA and 2% SDS at 37°C for 15min. De-crosslinking was performed overnight at 65°C. RNA was removed by 1h incubation with RNAse A (Peqlab) at 37°C, followed by 1h incubation with Proteinase K (Peqlab) at 42°C. DNA was purified using PCR Purification Kit (Qiagen) according to the manufacturer’s instructions. All antibodies used are listed in Supplementary Information Table 2.