Intestinal epithelial cells were isolated as above and were further purified for flow cytometry and cell sorting (5). The preserved IECs were sent to MedGenome, Foster City, CA, USA). Nuclei were isolated from the IECs and incubated with pre-loaded Tn5 transposase (Cat # FC-121-1030, Illumina, CA, USA) and sequencing adapters. The assembled protein A-Tn5 adapter transposome was activated by Mg2+ to generate adapter-flanked DNA fragments cut near the proteins of interest. The transposed DNA was then extracted, and PCR amplified using NEBNext High-Fidelity PCR Master Mix (Cat # M0541S, New England Biolabs, MA, USA). The library was purified with AMPure XP Magnetic Beads (Cat # A63880, Beckman Coulter, CA, USA), and its quality was assessed using a BioAnalyzer High-Sensitivity DNA Analysis kit (Cat # 5067–4626, Agilent, CA, USA).