Tight junctions (TJs) establish the epithelial barrier and are thought to form a membrane fence to regulate epithelial polarity, although the roles of TJs in epithelial polarity remain controversial. Claudins constitute TJ strands in conjunction with the cytoplasmic scaffolds ZO-1 and ZO-2 and play pivotal roles in epithelial barrier formation. However, how claudins and other TJ membrane proteins cooperate to organize TJs remains unclear. Here, we systematically knocked out TJ components by genome editing and show that while ZO-1/ZO-2–deficient cells lacked TJ structures and epithelial barriers, claudin-deficient cells lacked TJ strands and an electrolyte permeability barrier but formed membrane appositions and a macromolecule permeability barrier. Moreover, epithelial polarity was disorganized in ZO-1/ZO-2–deficient cells, but not in claudin-deficient cells. Simultaneous deletion of claudins and a TJ membrane protein JAM-A resulted in a loss of membrane appositions and a macromolecule permeability barrier and in sporadic epithelial polarity defects. These results demonstrate that claudins and JAM-A coordinately regulate TJ formation and epithelial polarity.

Claudin‐based tight junctions (TJs) are formed at the most apical part of cell–cell contacts in epithelial cells. Previous studies suggest that scaffolding proteins ZO‐1 and ZO‐2 (ZO proteins) determine the location of TJs by interacting with claudins, but this idea is not conclusive. To address the role of the ZO proteins binding to claudins at TJs, a COOH‐terminal PDZ domain binding motif‐deleted claudin‐3 mutant, which lacks the ZO protein binding, was stably expressed in claudin‐deficient MDCK cells. The COOH‐terminus‐deleted claudin‐3 was localized at the apicolateral region similar to full‐length claudin‐3. Consistently, freeze‐fracture electron microscopy revealed that the COOH‐terminus‐deleted claudin‐3‐expressing cells reconstituted belts of TJs at the most apical region of the lateral membrane and restored functional epithelial barriers. These results suggest that the interaction of claudins with ZO proteins is not a prerequisite for TJ formation at the most apical part of cell–cell contacts.

All sectors of the economy are striving for sustainable development; therefore, corporate social responsibility (CSR) disclosure is of great interest. Vietnamese banks have been disclosing CSR information in recent years; however, the manner and quality of these bank disclosures are inconsistent. For better judgment, this study evaluates the disclosure of CSR information by Vietnamese banks, compares changes in those disclosures over time, and tracks differences in disclosure quantity and quality among different groups of banks over the ten-year period of 2012 to 2021. In addition to a semiobjective approach, descriptive statistics is the main method used in this study. The quality of CSR information between listed and unlisted banks showed no significant difference, although more complete CSR information is disclosed by Statedowned banks, in comparison with commercial banks. The quality of CSR disclosure tends to increase over time in all five categories including economy, community, environment, employees, and products. In which, banks report more information relating to the economy and community factors. The results provide interesting findings and essential suggestions for CSR disclosures by Vietnamese banks, toward the goals of profitability, competitiveness, and sustainable development.

Epithelia must be able to resist mechanical force to preserve tissue integrity. While intercellular junctions are known to be important for the mechanical resistance of epithelia, the roles of tight junctions (TJs) remain to be established. We previously demonstrated that epithelial cells devoid of the TJ membrane proteins claudins and JAM-A completely lack TJs and exhibit focal breakages of their apical junctions. Here, we demonstrate that apical junctions undergo spontaneous fracture when claudin/JAM-A-deficient cells are exposed to mechanical stress. The junction fracture was accompanied by actin disorganization, and actin polymerization was required for apical junction integrity in the claudin/JAM-A-deficient cells. Further deletion of CAR resulted in the disruption of ZO-1 molecule ordering at cell junctions, accompanied by severe defects in apical junction integrity. These results demonstrate that TJ membrane proteins regulate the mechanical resistance of the apical junctional complex in epithelial cells.