Comparative bulk RNAseq between EpH4 WT and Cldn-null cells

The claudin (CLDN) family, comprising 27 members, includes crucial cell–cell adhesion molecules that form tight junctions (TJs), essential for paracellular barrier and channel functions. The functional diversity among CLDNs may lead to diversity of TJs, contributing to various biological systems and pathological processes. To characterize the functional diversity of CLDNs, we developed a first-ever complete Cldn-null EpH4 epithelial cell line. This cell line was used for the expression of single Cldn family members, uncovering their specific intrinsic properties. Unlike the conventional binary classification of CLDNs as either paracellular barrier or channel forming, we discovered a novel classification axis where CLDNs form TJs autonomously or non-autonomously, exhibiting extensive variation in ion conductivity and selectivity, leading to an innovative classification. This classification offers a fundamental framework for understanding the mechanisms underlying TJ diversity in vivo, and provides a basis for the development of therapies targeting the epithelial barrier. Overall design: To investigate the overall gene expression profiling, we conducted a comparative bulk RNAseq analysis between EpH4 WT and Cldn-null cells.