Effects of PAX8 depletion on gene expression in proximal tubule epithelial cells.

PAX2 and PAX8 are homologous DNA-binding proteins that orchestrate kidney development, regulate urine concentration in the kidney medulla, and contribute to sensitivity to and recovery from acute kidney injury. In some contexts, Pax proteins can recruit KMT2C/D histone methyl-transferase complexes that deposit histone H3K4 methylation marks to promote transcription or recruit the Polycomb Repressor Complex to silence gene expression. However, the spectrum of targets and functions of Pax proteins in kidney physiology remains poorly defined. This project aimed to identify genes regulated by PAX proteins in the proximal tubule. Proximal tubule epithelial cells were derived from mice with floxed Pax2 and Pax8 alleles and expressing a constitutive tamoxifen-response CreERT2 (mice described in PMID: 32381599). During propagation, Pax2 was spontaneously recombined, yielding a Pax2-null, Pax8-conditional cell line which was named PT-22. In the experiments in this submission, PAX8 was depleted from PT-22 cells with tamoxifen and gene expression was measured over time to identify likely activating and repressive targets of PAX8.